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PPC 0022 Metaprogramming API #25

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merged 11 commits into from
Dec 7, 2023
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PPC 0022 Metaprogramming API #25

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7da5fd2
Initial writings
leonerd Jul 29, 2023
5487207
Various small adjustments and rewordings; added new Open Issues points
leonerd Oct 15, 2022
53cda48
s/RFC/PPC/ in new doc
leonerd Jul 29, 2023
2a79dcf
Lots of rewriting in places; general updates
leonerd Aug 15, 2023
4a274b9
Add further thoughts about whether the glob shapes should be supported
leonerd Aug 15, 2023
4b92806
Add an optional $ref parameter to $metaglob->add_scalar et.al.
leonerd Aug 15, 2023
c10ed8b
No need for separate get_variable / get_subroutine; just have a singl…
leonerd Aug 15, 2023
9904e35
Make globs an inherent part of the API shape, not optionally
leonerd Aug 15, 2023
680dcc5
Fix type of coderef's sigil
leonerd Aug 16, 2023
28aefdf
Also permit a GLOB ref to ::for_reference
leonerd Aug 16, 2023
31cd9f9
Escape the asterisk when quoted as the glob sigil, to avoid confusing…
leonerd Aug 31, 2023
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No need for separate get_variable / get_subroutine; just have a singl… 
…e for_reference()
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@leonerd
leonerd committed Aug 30, 2023
commit c10ed8b59849a63da3fad10982b2f689ff0fb5ba
18 changes: 5 additions & 13 deletions ppcs/ppc0022-metaprogramming.md
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Expand Up @@ -69,25 +69,17 @@ Returns a list of sub-packages within the given base package name, each as a met

Some less common functions that may still be useful in some situations. These functions can be used to obtain meta-programming object instances in ways other than walking the symbol table for given names.

#### `get_variable`
#### `for_reference`

```perl
$metavar = meta::get_variable($varref);
$metavar = meta::for_reference($ref);
```

Given a reference to a package variable, returns a meta-variable object instance to represent it. If `$varref` is not a SCALAR, ARRAY or HASH reference, an exception is thrown.
Given a reference to a package variable or subroutine, returns a meta-object instance to represent it. If `$varref` is not a SCALAR, ARRAY, HASH or CODE reference, an exception is thrown.
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You allow get_symbol to return a GLOB, but don't allow a globref to be passed in here.

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Ahyes; might as well allow GLOBrefs too. Fixed in 387d25b


*Note:* It is currently unspecified what happens if the reference refers to a lexical or anonymous variable, rather than a package one. This PPC does not specify any useful behaviour for such instances, but it's possible that future abilities may be added that become useful on lexical variables or anonymous containers.

#### `get_subroutine`
Anonymous subroutines should be supported; at least in order to obtain a meta-object to represent them so that methods like `set_subname` can be called on them.

```perl
$metasub = meta::get_subroutine($subref);
```

Given a CODE reference, returns a meta-subroutine object instance to represent it. If `$subref` is not a CODE reference, an exception is thrown.

This is primarily useful for working with newly-constructed anonymous functions, in order to give them a valid name by calling `set_subname` for instance.
*Note:* It is currently unspecified what happens if the reference refers to a lexical or anonymous variable, rather than a package one. This PPC does not specify any useful behaviour for such instances, but it's possible that future abilities may be added that become useful on lexical variables or anonymous containers.

### Methods on Meta-Package Objects

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