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https://issues.apache.org/jira/browse/FREEMARKER-107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16949490#comment-16949490
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Pascal Proulx edited comment on FREEMARKER-107 at 10/11/19 2:15 PM:
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I see what you mean. I haven't thought about that case because I completely
avoided using positional arguments with macros, so it wouldn't be an issue for
me, and would have created issues, you're probably right on that. It was never
even a question.
Even for functions: what I did for many functions was to take a simple "args"
map instead of positional arguments - or after one or two positional arguments
- and often would reuse an argument as both the args map and as a positional
argument using a type check (args?is_hash_ex, args?is_string, ...) - sometimes
you see this in javascript libraries - because parameter names become essential
for readability in *.ftl when you go past 2-3 parameters... all to say I tried
to avoid positional arguments. Similarly I'm not sure I will use ?spread_args
as much with functions, but will see.
was (Author: pplx):
Ah I see what you mean. I haven't thought about that case because I completely
avoided using positional arguments with macros, so it wouldn't be an issue for
me, and would have created issues, you're probably right on that. It was never
even a question.
Even for functions: what I did for many functions was to take a simple "args"
map instead of positional arguments - or after one or two positional arguments
- and often would reuse an argument as both the args map and as a positional
argument using a type check (args?is_hash_ex, args?is_string, ...) - sometimes
you see this in javascript libraries - because parameter names become essential
for readability in *.ftl when you go past 2-3 parameters... all to say I tried
to avoid positional arguments. Similarly I'm not sure I will use ?spread_args
as much with functions, but will see.
> Hash expansion to macro arguments (Python **kwargs style)
> ---------------------------------------------------------
>
> Key: FREEMARKER-107
> URL: https://issues.apache.org/jira/browse/FREEMARKER-107
> Project: Apache Freemarker
> Issue Type: New Feature
> Components: engine
> Affects Versions: 2.3.28
> Reporter: Pascal Proulx
> Priority: Major
>
> Hello,
> We heavily rely on Freemarker macros to build a helper template API, but have
> had to make large workarounds for passing contents of hashes as macro
> arguments, for several years. (In truth I should have made this ticket much
> sooner!)
> It would help greatly simplify our work to have hash expansion to macro
> arguments, like this:
> {code:java}
> <#macro myMacro arg1 arg2 arg3="value3">...</#macro>
> <#assign myHash = {"arg1":"value1", "arg2":"value2"}>
> <@myMacro **myHash/><#-- the hash contents are passed as parameters, instead
> of the hash itself -->
> {code}
> This exists in Python:
> {code:java}
> def test_var_args_call(arg1, arg2, arg3):
> pass
> kwargs = {"arg3": 3, "arg2": "two"}
> test_var_args_call(1, **kwargs)
> {code}
> Essentially the hash contents fill in any arguments not explicitly specified.
> For the case where arguments are specified in addition to the hash, you may
> need to decide on a good syntax, e.g.:
> {code:java}
> <@myMacro arg1="value1" **myHash/>{code}
> This example doesn't have much precedent in freemarker syntax but is fairly
> understandable.
> Although we don't need it nearly as much, the same could be done with lists
> and function arguments:
> {code:java}
> <#function myFunc arg1 arg2>...</#function>
> <#assign myList = ["val1", "val2"]>
> ${myFunc(*myList)}
> <#assign myList = ["val2"]>
> ${myFunc("val1", *myList)}
> {code}
> Again similar to Python:
> {code:java}
> def test_var_args_call(arg1, arg2, arg3):
> pass
> args = ("two", 3)
> test_var_args_call(1, *args)
> {code}
> You might want this for consistency, although in practice the hash expansion
> will be many times more useful to us.
> If there's a lack a manpower I could try to see what I can do digging into
> the source, but wanted to bring this up for discussion first. It doesn't
> appear hard to implement to dump a hash into the macro args map, but there is
> defining the syntax.
> We use Freemarker 2.3.28 at the moment.
> Thank you
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