function signatures in XML

Robert Stoll wrote on 05/03/2015 13:44:

Heya,

Does PHP store somewhere meta-information of all internal functions (and operators) in a portable format such as XML?
I would like to extract information such as

• parameters including types
• return type

automatically. Preferably each overload of a function but I guess that does not exist.
For instance, str_replace has overloads:
string x string x string x (&int) -> string
string x string x array x (&int) -> array
array x string x string x (&int) -> string
array x array x string x (&int) -> string
array x array x array x (&int) -> array

Unfortunately, the manual as such is not precise enough for my needs.

I'm not an expert, so can't give a final answer, but a couple of bits
I've picked up from lurking for the last few months and digging into the
source out of curiosity:

• The manual entries for new extensions are actually built using
  Reflection, with a script called "docgen" here:
  http://svn.php.net/viewvc/phpdoc/doc-base/trunk/scripts/docgen/
• I believe the reflection in turn comes from the "ARG_INFO" macros,
  e.g. http://lxr.php.net/xref/PHP_TRUNK/ext/standard/basic_functions.c#2332
• The overloads you mention aren't (in most cases) really overloads, the
  C functions parse arguments using a bunch of macros referred to as
  "ZPP", and can do various things with them, including just accepting a
  zval (i.e. parameter of any type) and interrogating that C structure to
  see what type it is. For instance, str_replace does that here:
  http://lxr.php.net/xref/PHP_TRUNK/ext/standard/string.c#4130
• As far as I know, the return type isn't declared anywhere, it's just
  an output parameter which points at a zval, and the code can set it to
  whatever it wants. I may be missing something there though.

As you can see, the arg_info just has the parameter names and by-ref
flag, and in the definition itself there's just a bunch of code branches
for "if (Z_TYPE_P(search) != IS_ARRAY)", "if (Z_TYPE_P(replace) !=
IS_STRING)", etc, so there's no way of recovering a table of valid type
combinations like that without a LOT of code analysis.

This is one of the things that makes consistency difficult with scalar
type hinting - internal functions, although written in a strictly typed
language, aren't actually type hinted!

Regards,

Rowan Collins
[IMSoP]