[PD-dev] type of A_GIMME argc?

[IOhannes m zmoelnig via Pd-dev]

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recently, i received a bug-report for the "puredata" Debian-package,
that warned of conflicting declarations of the glist_scalar() function.

the problem seems to be, that glist_scalar() uses "int argc" for it's
A_GIMME argument in the declaration in g_canvas.c, but uses "t_int
argc" in the function definition in g_scalar.c.
now "t_int" is defined as a "pointer-sized integer", which is a "long
int" on amd64, thus incompatible with the 32bit "int".

it is often tempting to use "t_int" whenever possible, as it is the
Pd-native integer type.
unfortunately this can (and will) break binary compatibility in some
cases.

i think it should be *well documented* which types to use.
e.g. the only way to find out how to use A_GIMME is reading the source
code (where we have at least 4 occurences that use "t_int"
(glist_scalar(), curve_new(), plot_new() and drawnumber_new()) and a
lot more (>200) uses of "int".

also t_listmethod and t_anymethod in m_imp.h seem to suggest that
"int" is the correct type (though "m_imp.h" was historically
considered a "private" header, not meant for documentation).

i think it's necessary to fix all uses of "t_int argc" to "int argc".

additionally i think it would be good to:
- - clearly document the function-signature for (A_GIMME) callbacks (and
while doing so, move the various callback-typedefs from m_imp.h to m_pd.h)

- - split the generic "t_int" type into multiple names, that suggest
their usage.
afaict, the original use of "t_int" is for the dsp process function
(t_perfroutine) , though the name does not suggest anything like this.
probably we should move to a new (probably even more pointer-like) type
 typedef t_perfarg void*;
and replace all other uses of t_int (e.g. the return value of
"atom_getint()" or the struct-member "t_resample.upsample") by other
types, e.g. "int",
for compatibility reasons, we might need to keep the two (or more)
types the same size, but they should be separated on a semantic level.


msdr
IOhannes

PS: it's pure coincidence that we had this recent conversation on
pd-list, where argc was declared "short".

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=750168
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