Is it possible in Swift to do what I think of as meta programming.
For example can I pass a variable in place of an object value.
Say I have a constant struct called Colors which has several attributes like this:
struct Colors {
static let grayUltraLight = "#F2F2F2"
static let grayLight = "#C4C4C4"
static let grayDark = "#585250"
}
I can user Colors.grayLight to get its hex value but is it possible to pass the key value as a variable? Something like Colors.myVal where myVal has been set to one of the keys?
Like myVar = "grayDark" and then asking for Colors.myVar and having it return "#585250"
I come from a Ruby development background where this is possible and it's been handy for DRYing up repetitive code.
Related
I'm working on a Wordclock with an Arduino so we're in C++. I want to save the corresponding Pixels and length of the words in a type so I can call a function that takes the Word to display as a property.
So here is what I came up with:
(Pseudocode)
type WORD
property1 = pixelPosition (integer)
property2 = wordLength (also integer)
I also would like to implement all the values in a compact form like in a enum like this:
word1= (123, 3);
Instead of this:
word1.pixelPos = 123;
word1.length = 3;
Unfortunately I didnt find a way to set two values in an enum. Is there a way I can create a custom type and set it to be the kind of type I want to enum?
disclaimer: My title may not be accurate as far as what I would like to accomplish, but I can update if someone can correct my terminology
I have 2 functions, each with a separate purpose and usable on its own, but occasionally I would like to combine the two to perform both actions at once and return a single result, and to do this I would like to assign to a variable name
I know I can create a 3rd function that does basically what I want as it is really simple.. though it's become a bit of a challenge to myself to find a way of doing this
def str2bool(string):
return string.lower() in ("yes", "true", "t", "1")
def get_setting(string):
if string == 'cat':
return 'yes'
else:
return 'no'
VALID_BOOL = str2bool(get_setting)
print VALID_BOOL('cat')
So basically I would like to assign the combination of the 2 functions to a variable that I can call and pass in the string parameter to evaluate
In my real world code, get_setting() would retrieve a user setting and return the value, I would then like to test that value and return it as a boolean
Again I know I can just create a 3rd function that would get the value and do the quick test.. but this is more for learning to see if it can be done as I'm trying to do.. and so far my different variations of assigning and calling aren't working, is it even possible or would it turn too complex?
Using lambda is easy, but i don't know if it is exactly what you are looking for.
Example:
f = lambda astring : str2bool(get_setting(astring))
Outputs:
>>> f('cat')
True
How do I write a simple ABAP Unit Assert statement to check if any call, expression or other statement evaluates to true?
I can't see any basic assert() or assert_true() methods in CL_AUNIT_ASSERT while I'd expect those to be very common. I can approximate such an assert as follows, but is there no cleaner way?
cl_aunit_assert=>assert_equals(
act = boolc( lv_value > 100 OR lv_value < 2 )
exp = abap_true ).
cl_aunit_assert=>assert_equals(
act = mo_model->is_active )
exp = abap_true ).
Depending on your SAP NetWeaver stack you can (or should) use the updated ABAP Unit Class CL_ABAP_UNIT_ASSERT. This class is available at a Basis-Release >= 7.02. SAP declared this class as 'FINAL' so it´s impossible to inherit from it, but on the other side they added some ASSERT-Methods like the ASSERT_TRUE Method!
Here is a possible usage of this method:
cl_abap_unit_assert=>assert_true(
exporting
act = m_ref_foo->is_bar( l_some_var )
msg = 'is_bar Method fails with Input { l_some_var }'
).
For the releases I have access to, there's probably no shorter way than the one you outlined. You can create a subclass of CL_AUNIT_ASSERT and add your own static ASSERT_TRUE method. It's not a bad idea to do so and at the same time make your local ABAP Unit test class a subclass of that ZCL_AUNIT_ASSERT - this way, you can omit the cl_aunit_assert=> prefix which will save some keystrokes.
You cannot see such methods because there is no boolean type in ABAP.
While in Java, C++ or C, you are able to assign a result of a condition to a variable, like this
int i = 5;
boolean result = i > 3;
You cannot do the same thing in ABAP as there is no boolean type. Therefore what in other languages is a one liner, in ABAP it will always be more prolix.
DATA: i TYPE i VALUE 5.
DATA: result TYPE abap_bool.
IF i > 3.
result = abap_true.
ELSE.
result = abap_false.
ENDIF.
The thing you used seems to be a new feature, that has been recently added to the language and most of the customers will not be using for a long time. Also the CL_AUNIT_ASSERT class was created way before the new elements came to the language.
So right now, there is a possibility to write the above thing as one liner. However there is still no boolean type in the language.
DATA: i TYPE i VALUE 5.
DATA: result TYPE abap_bool.
result = boolc( i > 3 ).
On the other hand, there is no boolean type, but you could simply use ASSERT_INITIAL or ASSERT_NOT_INITIAL in this case, as boolean is emulated by either X (true) or space (false). The latter is an initial value in ABAP.
The cleanest way is to just fail:
if value > limit.
cl_abap_unit_assert=>fail( ).
endif.
Or a more informative:
cl_abap_unit=>fail( msg = 'Limit exceeded' ).
Scala noob i'm afraid:
I have the following declared class variable which will the objects I read from the database:
val options = mutable.LinkedList[DivisionSelectOption]()
I then use JPA to get a List of all rows from a table:
val divisionOptions = em.createNamedQuery("SelectOption.all", classOf[SelectOption]) getResultList
/* Wrap java List in Scala List */
val wrappedOptions = JListWrapper.apply(divisionOptions)
/* Store the wrappedOptions in the class variable */
options += wrappedOptions
However, the last line has an error:
Type Expected: String, actual JListWrapper[SelectOption]
Can anyone help with what I am doing wrong? I'm just trying to populate the options object with the result of the DB call.
Thanks
What (probably) is happening is that a JlistWrapper[SelectOption] isn't a DivisionSelectOption, so the method += isn't applicable to it. That being the case, it is trying other stuff, and giving a final error on this:
options = options + wrappedOptions
That is a rewriting Scala can do to make things like x += 1 work for var x. The + method is present on all objects, but it takes a String as parameter -- that's so one can write stuff like options + ":" and have that work as in Java. But since wrappedOptions isn't a String, it complains.
Roundabout and confusing, I know, and even Odersky regrets his decision with regards to +. Let that be a lesson: if you thing of adding a method to Any, think really hard before doing it.
I have what I believe to be an embarrassingly simple problem, but three hours of googling and checking stackoverflow have not helped.
Let's say I have a very simple piece of code:
def secret_formula(started):
jelly_beans = started*500
jars = jelly_beans/1000
crates = jars/100
return jelly_beans,jars,crates
start_point = 10000
print("We'd have {} beans, {} jars, and {} crates.".format(secret_formula(start_point)))
What happens is I get the "IndexError: tuple index out of range". So I just print the secret_formula function to see what it looks like, and it looks like this:
(5000000, 5000.0, 50.0)
Basically, it is treating the output as one 'thing' (I am still very new, sorry if my language is not correct). My question is, why does it treat it like this and how do I make it pass the three outputs (jelly_beans, jars, and crates) so that it formats the string properly?
Thanks!
The format function of the string take a variable number of argument. The secret_formula function is returning a tuple. You want to convert that to a list of arguments. This is done using the following syntax:
print("We'd have {} beans, {} jars, and {} crates.".format(*secret_formula(start_point)))
The important par is the * character. It tell that you want to convert the following iterable into a list of argument to pass to the function.