I'm writing an application that allows the user to configure the output using templates. For example:
Variables:
name = "BoppreH"
language = "Python"
Template:
My name is {name} and I like {language}.
Output:
My name is BoppreH and I like Python.
This works fine for simple data, like strings and numbers, but I can't find a good syntax for lists, more specifically for their delimiters.
fruits = ["banana", "apple", "watermelon"]
I like {???}.
I like banana, apple, watermelon.
In this case the desired delimiter was a comma, but how can the user specify that? Is there some template format with this feature?
I'm more concerned about making the syntax simple to understand, regardless of language or library.
Implement filters, and require their use for non-scalar types.
I like {fruits|join:", "}.
Typically, a list contains an unknown number of members, and sometimes variables/placeholders of its own. An example might be listing the name of a person along with their phone numbers. The desired output might look something like this:
John Doe
555-1212
555-1234
In a templating system that supported this, you'd need two types of variables: One that designated a placeholder for a value (like the curly braces you're using now), and another to denote the start and end of the list. So, something like this:
{name}
{{phone_numbers}}{phone}{{/phone_numbers}}
Your array of values might look like this:
values = [names: "John Doe", phone_numbers: [ phone: "555-1212", phone: "555-1234"]]
Each value in the "phone_numbers" array would create a new instance of everything that existed between {{phone_numbers}} and {{/phone_numbers}}, placing the values contained within those two "tags".
Related
I am using data sources in Terraform to fetch a list of ids of my security groups as such:
data "aws_security_groups" "test" {
filter {
name = "group-name"
values = ["the-name"]
}
}
output "security_group_id" {
value = "The id is ${data.aws_security_groups.test.ids[*]}"
}
However, this is giving me the following error:
Error: Invalid template interpolation value
on main.tf line 11, in output "security_group_id":
11: value = "The id is ${data.aws_security_groups.test.ids[*]}"
|----------------
| data.aws_security_groups.test.ids is list of string with 1 element
Cannot include the given value in a string template: string required.
But if I use data.aws_security_groups.test.ids[0] instead it displays the ID.
Can someone help me to display the list of IDs?
First, I want to note that you don't necessarily need to combine this list with a string message at all if you don't want to, because Terraform will accept output values of any type:
output "security_group_ids" {
value = data.aws_security_groups.test.ids
}
If having them included as part of a bigger string is important for your underlying problem then you'll need to make a decision about how you want to present these multiple ids in your single string. There are various different ways you could do that, depending on what you intend to do with this information.
One relatively-straightforward answer would be to make the string include a JSON representation of the list using jsonencode, like this:
output "security_group_id_message" {
value = "The ids are ${jsonencode(data.aws_security_groups.test.ids)}"
}
If you want a more human-friendly presentation then you might prefer to use a multi-line string instead, in which case you can customize the output using string templates.
output "security_group_id_message" {
value = <<-EOT
The ids are:
%{ for id in data.aws_security_groups.test.ids ~}
- ${id}
%{ endfor ~}
EOT
}
Or, for an answer somewhere in between, you could use join to just concatenate the values together with a simple delimiter, like this:
output "security_group_id_message" {
value = "The ids are ${join(",", data.aws_security_groups.test.ids)}"
}
Note that I removed the [*] from your reference in all of these examples, since it isn't really doing anything here: data.aws_security_groups.test.ids is already an iterable collection, and so is compatible with all of the language features I used in the examples above.
IIRC the provider considers this ids attribute to be a set of strings rather than a list of strings, and so that [*] suffix could potentially be useful in other situations to force converting the set into a list if you need it to be typed that way, although if that is your intent then I'd suggest using one of the following instead so that it's clearer to a future reader what it does:
sort(data.aws_security_groups.test.ids) (if it being in lexical order is important to the behavior; Terraform uses lexical sorting by default anyway, but calling sort is a good prompt to a reader unfamiliar with Terraform to look up that function to see what the actual sort order is.)
tolist(data.aws_security_groups.test.ids) (functionally equivalent to sort above when it's a set of strings, but avoids the implication that the specific ordering is important, if all that matters is that it's a list regardless of the ordering)
I was watching an old programming tutorial about loops and ranges in Kotlin and I tried to copy that same code but apparently my Kotlin version did not respond well.
The original Source Code was:
val capitals= listOf("London", "Paris", "Rome", "Madrid")
for(capital in capitals){
println(capital)
}
I have 2 Questions: First, why use capital and capitals again?
Also when I introduce the source code kotlin adds these symbols <>.
Updated Kotlin code (The one code causing me concern):
val capitals = listOf<> // (this is normal the problem is <>)
When I add the listOf to the value this automatically shows up.
Also, I don't know why the for(capital in capitals) {...} fails.
The code you provided works as expected:
val capitals = listOf("London", "Paris", "Rome", "Madrid")
for(capital in capitals){
println(capital)
}
Prints:
London
Paris
Rome
Madrid
why use capital and capitals again?
Using capital variable in the for loop you store each value of capitals list by iterating through it to handle it as you want.
When you declare a list like this val capitals = listOf("London", "Paris", "Rome", "Madrid"), it implies that you want to access its elements later. You can access its elements only by its name capitals, which you do in the for loop.
As for generics, classes or interfaces in Kotlin can have type parameters, which defined in <> brackets. List is one of such classes.
If the generic parameters can be inferred, for example you can omit the type arguments and <> brackets.
In code below named arguments have to be duplicated, is there a way to shorten the expression?
struct Figure
getter id : String
getter hash : String
getter title : String
def initialize(#id, #hash, #title)
end
end
id = "Figure 1", hash = "123", title = "Some figure"
Figure.new id: id, hash: hash, title: title
Something like code below, yet keep it named not positional?
Figure.new id, hash, title
or maybe
Figure.new{ id, hash, title }
I don't know of a way to shorten this.
I think this would be a dangerous semantic when you tie the names of local variables to the names of method arguments because changing things on one place would have unforeseeable effects in another place.
Using positional arguments should be fine for most use cases. And in cases where you want to skip some arguments, you can just combine positional and named arguments.
I'm using textacy's pos_regex_matches method to find certain chunks of text in sentences.
For instance, assuming I have the text: Huey, Dewey, and Louie are triplet cartoon characters., I'd like to detect that Huey, Dewey, and Louie is an enumeration.
To do so, I use the following code (on testacy 0.3.4, the version available at the time of writing):
import textacy
sentence = 'Huey, Dewey, and Louie are triplet cartoon characters.'
pattern = r'<PROPN>+ (<PUNCT|CCONJ> <PUNCT|CCONJ>? <PROPN>+)*'
doc = textacy.Doc(sentence, lang='en')
lists = textacy.extract.pos_regex_matches(doc, pattern)
for list in lists:
print(list.text)
which prints:
Huey, Dewey, and Louie
However, if I have something like the following:
sentence = 'Donald Duck - Disney'
then the - (dash) is recognised as <PUNCT> and the whole sentence is recognised as a list -- which it isn't.
Is there a way to specify that only , and ; are valid <PUNCT> for lists?
I've looked for some reference about this regex language for matching PoS tags with no luck, can anybody help? Thanks in advance!
PS: I tried to replace <PUNCT|CCONJ> with <[;,]|CCONJ>, <;,|CCONJ>, <[;,]|CCONJ>, <PUNCT[;,]|CCONJ>, <;|,|CCONJ> and <';'|','|CCONJ> as suggested in the comments, but it didn't work...
Is short, it is not possible: see this official page.
However the merge request contains the code of the modified version described in the page, therefore one can recreate the functionality, despite it's less performing than using a SpaCy's Matcher (see code and example -- though I have no idea how to reimplement my problem using a Matcher).
If you want to go down this lane anyway, you have to change the line:
words.extend(map(lambda x: re.sub(r'\W', '', x), keyword_map[w]))
with the following:
words.extend(keyword_map[w])
otherwise every symbol (like , and ; in my case) will be stripped off.
We have a file that contains data that we want to match to a case class. I know enough to brute force it but looking for an idiomatic way in scala.
Given File:
#record
name:John Doe
age: 34
#record
name: Smith Holy
age: 33
# some comment
#record
# another comment
name: Martin Fowler
age: 99
(field values on two lines are INVALID, e.g. name:John\n Smith should error)
And the case class
case class Record(name:String, age:Int)
I Want to return a Seq type such as Stream:
val records: Stream records
The couple of ideas i'm working with but so far haven't implemented is:
Remove all new lines and treat the whole file as one long string. Then grep match on the string "((?!name).)+((?!age).)+age:([\s\d]+)" and create a new object of my case class for each match but so far my regex foo is low and can't match around comments.
Recursive idea: Iterate through each line to find the first line that matches record, then recursively call the function to match name, then age. Tail recursively return Some(new Record(cumulativeMap.get(name), cumulativeMap.get(age)) or None when hitting the next record after name (i.e. age was never encountered)
?? Better Idea?
Thanks for reading! The file is more complicated than above but all rules are equal. For the curious: i'm trying to parse a custom M3U playlist file format.
I'd use kantan.regex for a fairly trivial regex based solution.
Without fancy shapeless derivation, you can write the following:
import kantan.regex._
import kantan.regex.implicits._
case class Record(name:String, age:Int)
implicit val decoder = MatchDecoder.ordered(Record.apply _)
input.evalRegex[Record](rx"(?:name:\s*([^\n]+))\n(?:age:\s*([0-9]+))").toList
This yields:
List(Success(Record(John Doe,34)), Success(Record(Smith Holy,33)), Success(Record(Martin Fowler,99)))
Note that this solution requires you to hand-write decoder, but it can often be automatically derived. If you don't mind a shapeless dependency, you could simply write:
import kantan.regex._
import kantan.regex.implicits._
import kantan.regex.generic._
case class Record(name:String, age:Int)
input.evalRegex[Record](rx"(?:name:\s*([^\n]+))\n(?:age:\s*([0-9]+))").toList
And get the exact same result.
Disclaimer: I'm the library's author.
You could use Parser Combinators.
If you have the file format specification in BNF or can write one, then Scala can create a parser for you from those rules. This may be more robust than hand-made regex based parsers. It's certainly more "Scala".
I don't have much experience in Scala, but could these regexes work:
You could use (?<=name:).* to match name value, and (?<=age:).* to match the age value. If you use this, remove spaces in found matches, otherwise name: bob will match bob with a space before, you might not want that.
If name: or any other tag is in comment, or comment is after value, something will be matched. Please leave a comment if you want to avoid that.
You could try this:
Path file = Paths.get("file.txt");
val lines = Files.readAllLines(file, Charset.defaultCharset());
val records = lines.filter(s => s.startsWith("age:") || s.startsWith("name:"))
.grouped(2).toList.map {
case List(a, b) => Record(a.replaceAll("name:", "").trim,
b.replaceAll("age:", "").trim.toInt)
}