I have recently started studying CodeSmith and I have a few questions.
I would like to make a template with 4 blocks.
Each block will be selected by the user.
How can I set the text block
(function) to selecting user?
How can I move blocks in separate
files?
For example there is a template
using System;
public class Hello3
{
public static void Main(string[] args)
{
Blocl 1
Blocl 2
Blocl 3
Blocl 4
}
}
Each of these blocks should be selected by the user. Each block is stored in a separate file.
Each block is a function. The output of one block enters to the input of another block.
P.S. Sorry for my bad english.
You could use a string property to set the name of a template or generated value. Then you would just render this string content during generation time.
Another option would be to create an enum that names different Code Blocks. Then inside of your template you could render a sub template or return some static text.
You could also create a custom dropdown list that allows you to choose a CodeSmith template. All of this logic would need to happen in a UITypeEditor and you would need to return a CodeTemplate using the API. This is a lot tougher than the first or second option.
I don't know how to do it using CodeSmith, but you would be better off using a "building-blocks" approach. AtomWeaver offers a way to build a code generator by smaller parts, called "Atoms". These Atoms are Templates that you can combine together.
In you case, I would build an Atom Template called cs_class:
The Template's Exec Code would be:
code([[
using System;
public class Hello3
{
public static void Main(string[] args)
{
{{code_blocks}}
}
}
]])
Notice the {{code_blocks}} marker. Another Template will put some code there.
Then, create the cs_code_block Atom Template. Use this code:
For the Admin Section:
under("cs_class")
For the Exec Section:
cursor("code_blocks")
code([[
<put user code here>
]])
The under() command helps you build an interactive modeling environment in AtomWeaver. Now, your user can create a model with one cs_class Atom, and then he can add as many cs_code_block Atoms as he wish. Executing the model will generate the desired code.
AtomWeaver lets you evolve your models and code generators. It's easy to start with a few lines and then grow it to obtain complete generators.
I know this is a very, very simplistic example of what you can build with AtomWeaver, but it's just to give you a quick idea of what you can accomplish.
Related
Let me elaborate on the title:
I want to implement a system that would allow me to enable/disable/modify the general behavior of my program. Here are some examples:
I could switch off and on logging
I could change if my graphing program should use floating or pixel coordinates
I could change if my calculations should be based upon some method or some other method
I could enable/disable certain aspects like maybe a extension api
I could enable/disable some basic integrated profiler (if I had one)
These are some made-up examples.
Now I want to know what the most common solution for this sort of thing is.
I could imagine this working with some sort of singelton class that gets instanced globally or in some other globally available object. Another thing that would be possible would be just constexpr or other variables floating around in a namespace, again globally.
However doing something like that, globally, feels like bad practise.
second part of the question
This might sound like I cant decide what I want, but I want a way to modify all these switches/flags or whatever they are actually called in a single location, without tying any of my classes to it. I don't know if this is possible however.
Why don't I want to do that? Well I like to make my classes somewhat reusable and I don't like tying classes together, unless its required by the DRY principle and or inheritance. I basically couldn't get rid of the flags without modifying the possible hundreds of classes that used them.
What I have tried in the past
Having it all as compiler defines. This worked reasonably well, however I didnt like that I couldnt make it so if the flag file was gone there were some sort of default settings that would make the classes themselves still operational and changeable (through these default values)
Having it as a class and instancing it globally (system class). Worked ok, however I didnt like instancing anything globally. Also same problem as above
Instancing the system class locally and passing it to the classes on construction. This was kinda cool, since I could make multiple instruction sets. However at the same time that kinda ruined the point since it would lead to things that needed to have one flag set the same to have them set differently and therefore failing to properly work together. Also passing it on every construction was a pain.
A static class. This one worked ok for the longest time, however there is still the problem when there are missing dependencies.
Summary
Basically I am looking for a way to have a single "place" where I can mess with some values (bools, floats etc.) and that will change the behaviour of all classes using them for whatever, where said values either overwrite default values or get replaced by default values if said "place" isnt defined.
If a Singleton class does not work for you , maybe using a DI container may fit in your third approach? It may help with the construction and make the code more testable.
There are some DI frameworks for c++, like https://github.com/google/fruit/wiki or https://github.com/boost-experimental/di which you can use.
If you decide to use switch/flags, pay attention for "cyclometric complexity".
If you do not change the skeleton of your algorithm but only his behaviour according to the objets in parameter, have a look at "template design pattern". This method allow you to define a generic algorithm and specify particular step for a particular situation.
Here's an approach I found useful; I don't know if it's what you're looking for, but maybe it will give you some ideas.
First, I created a BehaviorFlags.h file that declares the following function:
// Returns true iff the given feature/behavior flag was specified for us to use
bool IsBehaviorFlagEnabled(const char * flagName);
The idea being that any code in any of your classes could call this function to find out if a particular behavior should be enabled or not. For example, you might put this code at the top of your ExtensionsAPI.cpp file:
#include "BehaviorFlags.h"
static const enableExtensionAPI = IsBehaviorFlagEnabled("enable_extensions_api");
[...]
void DoTheExtensionsAPIStuff()
{
if (enableExtensionsAPI == false) return;
[... otherwise do the extensions API stuff ...]
}
Note that the IsBehaviorFlagEnabled() call is only executed once at program startup, for best run-time efficiency; but you also have the option of calling IsBehaviorFlagEnabled() on every call to DoTheExtensionsAPIStuff(), if run-time efficiency is less important that being able to change your program's behavior without having to restart your program.
As far as how the IsBehaviorFlagEnabled() function itself is implemented, it looks something like this (simplified version for demonstration purposes):
bool IsBehaviorFlagEnabled(const char * fileName)
{
// Note: a real implementation would find the user's home directory
// using the proper API and not just rely on ~ to expand to the home-dir path
std::string filePath = "~/MyProgram_Settings/";
filePath += fileName;
FILE * fpIn = fopen(filePath.c_str(), "r"); // i.e. does the file exist?
bool ret = (fpIn != NULL);
fclose(fpIn);
return ret;
}
The idea being that if you want to change your program's behavior, you can do so by creating a file (or folder) in the ~/MyProgram_Settings directory with the appropriate name. E.g. if you want to enable your Extensions API, you could just do a
touch ~/MyProgram_Settings/enable_extensions_api
... and then re-start your program, and now IsBehaviorFlagEnabled("enable_extensions_api") returns true and so your Extensions API is enabled.
The benefits I see of doing it this way (as opposed to parsing a .ini file at startup or something like that) are:
There's no need to modify any "central header file" or "registry file" every time you add a new behavior-flag.
You don't have to put a ParseINIFile() function at the top of main() in order for your flags-functionality to work correctly.
You don't have to use a text editor or memorize a .ini syntax to change the program's behavior
In a pinch (e.g. no shell access) you can create/remove settings simply using the "New Folder" and "Delete" functionality of the desktop's window manager.
The settings are persistent across runs of the program (i.e. no need to specify the same command line arguments every time)
The settings are persistent across reboots of the computer
The flags can be easily modified by a script (via e.g. touch ~/MyProgram_Settings/blah or rm -f ~/MyProgram_Settings/blah) -- much easier than getting a shell script to correctly modify a .ini file
If you have code in multiple different .cpp files that needs to be controlled by the same flag-file, you can just call IsBehaviorFlagEnabled("that_file") from each of them; no need to have every call site refer to the same global boolean variable if you don't want them to.
Extra credit: If you're using a bug-tracker and therefore have bug/feature ticket numbers assigned to various issues, you can creep the elegance a little bit further by also adding a class like this one:
/** This class encapsulates a feature that can be selectively disabled/enabled by putting an
* "enable_behavior_xxxx" or "disable_behavior_xxxx" file into the ~/MyProgram_Settings folder.
*/
class ConditionalBehavior
{
public:
/** Constructor.
* #param bugNumber Bug-Tracker ID number associated with this bug/feature.
* #param defaultState If true, this beheavior will be enabled by default (i.e. if no corresponding
* file exists in ~/MyProgram_Settings). If false, it will be disabled by default.
* #param switchAtVersion If specified, this feature's default-enabled state will be inverted if
* GetMyProgramVersion() returns any version number greater than this.
*/
ConditionalBehavior(int bugNumber, bool defaultState, int switchAtVersion = -1)
{
if ((switchAtVersion >= 0)&&(GetMyProgramVersion() >= switchAtVersion)) _enabled = !_enabled;
std::string fn = defaultState ? "disable" : "enable";
fn += "_behavior_";
fn += to_string(bugNumber);
if ((IsBehaviorFlagEnabled(fn))
||(IsBehaviorFlagEnabled("enable_everything")))
{
_enabled = !_enabled;
printf("Note: %s Behavior #%i\n", _enabled?"Enabling":"Disabling", bugNumber);
}
}
/** Returns true iff this feature should be enabled. */
bool IsEnabled() const {return _enabled;}
private:
bool _enabled;
};
Then, in your ExtensionsAPI.cpp file, you might have something like this:
// Extensions API feature is tracker #4321; disabled by default for now
// but you can try it out via "touch ~/MyProgram_Settings/enable_feature_4321"
static const ConditionalBehavior _feature4321(4321, false);
// Also tracker #4222 is now enabled-by-default, but you can disable
// it manually via "touch ~/MyProgram_Settings/disable_feature_4222"
static const ConditionalBehavior _feature4222(4222, true);
[...]
void DoTheExtensionsAPIStuff()
{
if (_feature4321.IsEnabled() == false) return;
[... otherwise do the extensions API stuff ...]
}
... or if you know that you are planning to make your Extensions API enabled-by-default starting with version 4500 of your program, you can set it so that Extensions API will be enabled-by-default only if GetMyProgramVersion() returns 4500 or greater:
static ConditionalBehavior _feature4321(4321, false, 4500);
[...]
... also, if you wanted to get more elaborate, the API could be extended so that IsBehaviorFlagEnabled() can optionally return a string to the caller containing the contents of the file it found (if any), so that you could do shell commands like:
echo "opengl" > ~/MyProgram_Settings/graphics_renderer
... to tell your program to use OpenGL for its 3D graphics, or etc:
// In Renderer.cpp
std::string rendererType;
if (IsDebugFlagEnabled("graphics_renderer", &rendererType))
{
printf("The user wants me to use [%s] for rendering 3D graphics!\n", rendererType.c_str());
}
else printf("The user didn't specify what renderer to use.\n");
I need to apply a lot of functions to the same piece of data in arbitrary order. Different people add different functions. I have created a system, that, after simplification, looks like that:
abstract_filter.h
class AbstractFilter {
void filter(data) = 0;
}
blue_filter.h
class BlueFilter: public AbstractFilter ...
red_filter.h ...
green_filter.h ...
parser.cpp
#include "blue_filter.h"
#include "red_filter.h" //so on
void Parse(const Data data) {
RedFilter redFilter();
redFilter.filter(data);
BlueFilter blueFilter();
blueFilter.filter(data);
....
}
I have hundreds of filters and people always forget to add them to the list or configure. Is it possible to write something like "take all classes from that group/folder and instantiate and put in array...."? I can't make them static or register filters in their constructors because several filtering stacks can be active in the same time.
All I want is to not have to manually enumerate all filters. Would be great to put them in place by just adding them to the project.
Write a python script which parses the filter directory entries an adds them to a generic factory or processing class. If the script runs on every build process the filters will always be taken care of.
I'm getting to grips with the Silverstripe framework and I've come across a strange error.
Say for example I want to create a new 'membership' page. Within mysite/code I have set up a membership.php page as follows:
class Membership extends Page {
}
class Membership_Controller extends Page_Controller {
}
Then I have created a membership.ss file within my templates/layout folder with some test output. I then do a dev build and create a page in the CMS of type 'membership'. On the front end if I click the new page form the nav bar membership I don't see the test text so it seems that the template is not being read?
Any ideas?
Thanks.
Alan.
There are several common pitfalls regarding templates:
how flushing works has changed several times in the past versions.
I will not explain the details here, as those are prossibly subject to change soon again.
However there are 2 things in the current version (3.1) that is of relevance here:
/dev/build does NOT flush at all
/dev/build?flush=1 does ONLY flush manifest and config (NO templates)
(dev build does not use the template, so there is no flushing the template performed)
this means that you have do do a ?flush=1 on a normal page, not just on dev/build
The Template file has to be named exactly like the class (I think its case sensitive)
check that the template file is not overwritten by another template file in another location. (eg if you have moduleName/templates/Foo.ss and themes/simple/templates/Foo.ss than the template of the theme will overwrite the module template
make sure the template is not empty (this causes an error in SilverStripe, at least in version 3.1)
Actions on a Controller can overwrite template ussage. here some examples:
// this will not use a template at all, it will just print "some string"
public function index() { return "some string"; }
// this will not use a template at all, it will output an empty string
public function index() { return; }
// this will use template named "Bar.ss"
public function index() { return $this->renderWith(array('Bar')); }
SilverStripe also provides a debug option to see what templates are used.
you can active it by 2 ways:
set source_file_comments in your yml config:
SSViewer:
# display template filenames as comments in the html output
source_file_comments: true
use the "URL Variable Tools": just add ?showtemplate=1 when viewing your website
when enabled, see the HTML source (CTRL+u in firefox) of the page
silverstripe will add comments to let you know what templates are used.
Make sure your class has a Page_Controller extension declared and named correctly. I recently had this issue. The page controller extension had a typo, so the template file was not being used.
So for example, if your page class is RidiculouslyNamedPage
class RidiculouslyNamedPage extends Page {
}
class RidiculouslyNamedPage_Controller extends Page_Controller {
}
Then in your themes/[theme-name]/templates/Layout/ folder you would have your RidiculouslyNamedPage.ss.
If you misspell RidiculouslyNamedPage_Controller the template will not get called.
I found the answer to the problem.
My .php was missing the following:
function getInfo() {
return $this->renderWith('Media');
}
ithout this the Media.ss file will not be used! Hopefully this will help other who might be getting to grips with SS!
I would like to write such a conditional fragment in a Go HTML template :
{{if isUserAdmin}}
<a href"/admin/nuke">Go to the big red nuclear button</a>
{{end}}
However, this is not directly possible because the template is not aware of the request that triggered its execution, so it cannot determine if the user is admin or not.
Is there some normal way to achieve this ?
In advance I point out that :
I do not want to use Pipelines for this specific data (see other question about this)
I acknowledge that only the handlers/controllers should deal with logic, and views should only do the rendering. But the condition {{if isUserAdmin}} is not logic itself, it's a necessary construct to leverage a boolean value already calculated by the controller.
The Funcs method can help, but is currently not lean enough for easily defining specific method isUserAdmin()
I would agree with Darshan Computing, I think the proper way of passing information from the request would be in the pipeline. You can have your data being split between the data you want to render and the context, e.g. by having your template data structure embed them both if you want to clearly separate the two:
type TemplateData struct {
*Content
*Context
}
Which gives this for example. You can then reuse some of your context/content information depending on what is shared and what is query specific.
Here is a working solution attempt (link to Playground) using Funcs to overwrite "isAdmin", after template compilation but before each execution (thanks to Valentin CLEMENT in other question).
But it has several flaws :
It is weird to declare a dummy empty "isAdmin" function before template compilation.
(Using Funcs several times is painful because I cannot just overwrite a single method, I have to provide a complete FuncMap with all the functions) edit : in fact previous funcs are not lost, i was wrong about that.
It is inherently not thread-safe and will fail when several goroutines alter and execute the same template
The normal thing to do is to simply pass your template a struct with whatever static data you like. Unless I've misunderstood what you're trying to do, there doesn't seem to be any need for Funcs here. Simplifying your example:
package main
import (
"html/template"
"os"
)
const hometmpl = `
{{if .IsAdmin}}
Go to the big red nuclear button
{{end}}
`
var t = template.Must(template.New("home").Parse(hometmpl))
func isAdmin(token string) bool {
const adminToken = "0xCAFEBABE"
return token == adminToken
}
func main() {
token := "0xCAFEBABE" // Or extracted from the http.Request
t.ExecuteTemplate(os.Stdout, "home", struct{IsAdmin bool}{isAdmin(token)})
}
I need to put scriptable NPC in my currect game project.
The project itself is developed in C++ language.
I will using Luabind to bind lua and c++.
I need to call NPC function when certain NPC clicked or timer to do something is activated.
Currently I stuck between 2 NPC script design.
Using a kind of npcname_action to differentiate every NPC.
This is kind of troublesome to give name to every different NPC.
I'm still thinking how to implement this in my project.
Example:
HotelBellboy12_Click() { .. }
HotelBellboy12_TimerAction() { .. }
Using name of function.
Every npc have it own lua file.
I'm thinking to load script into memory and when needed will be loaded into luaState using luaL_loadbuffer
Example:
OnClick() { .. }
OnTimerAction() { .. }
Which one is better and why?
You could use another design.
Take advantage of the fact that table keys and values can be any type.
Let's say npc is a table containing all NPC's. Its keys are NPC' names and its values are another table. This other table keys are the actions, and its values are the function for this actions.
So, if you want bob to jump when clicked on, and alice to cry after a timer, simply do :
npc.bob.click = function () jump() end
npc.alice.timer = function () cry() end
I've done something like this before and I used something similar to your #2 option. When the map loads I load a configuration Lua file containing all the NPC data; among that is the name of the script file used for the NPC.
When I need to load the NPC in the game I compile the Lua file. NPC's can use a 'model' NPC type to dictate most of the common behavior (for example a Merchant type or a Commoner type) which is specified in the NPC configuration. These model types provide all the basic functionality such as providing a trade window when clicked. The specific NPC's use functions like OnClick() to override their model and provide custom handlers.
This worked pretty well for me, although it ends up being a large volume of scripts if your game gets large.