procvar in the local state of the block, and then call it insde the
generated invoke routine. We can't call it directly there, because
due to visibility reasons it may not be accessible from a regular
procedure (e.g. if it is a strict private method)
git-svn-id: branches/blocks@28234 -
"reference to ...; cdecl;". The "reference to ..." syntax is what Delphi
uses for anonymous function references. The "cdecl;" indicates that this
is for the C-variant of such references, which is what blocks are
git-svn-id: branches/blocks@28233 -
o blocks are implemented as a variation of procedure variables
o declaration of a block variable: "test: procedure(c: char) is block;"
(C equivalent: (void)(^test)(char c) )
o the compiler automatically converts procedures/functions whose address
is passed to a block parameter or assigned to a block variable into
a "block". This consists of
1) generating a block descriptor (containing the size of the "block
literal" (see below) and the signature of the invocation function
encoded as an Objective-C selector)
2) generating a wrapper function around the original funcion (with C
calling convention), that has an extra first hidden parameter
(marked as vo_is_parentfp in the compiler) whose type is a pointer
to the describing "block literal"
3) generating the "block literal", which contains a pointer to an
external variable indicating whether this block captures context or
not, some flags (see compiler/blockutl.get_block_literal_flags for
info), a pointer to the wrapper function and a pointer to the
descriptor. In the future, it will also contain captured variables.
o right now, only global procedures/functions can be converted to blocks
(because they don't require state capturing). The next steps are (Object
Pascal) methods (not Objective-C methods, because Objective-C method
procvars don't exist) and finally nested functions
o on Mac OS X, the functionality will only work on Mac OS X 10.7 and later,
because we have to use the so-called "ABI.2010.3.16" to ensure that
our blocks aren't called as variadic functions by the runtime (which
came out after the Mac OS X 10.6 release)
o while the currently implemented functionality does not require any
library support at all, there's no use enabling it on other platforms
because unless it has been confirmed to work with a blocks runtime,
there's no point in using blocks (they're just somewhat bulky procvars
right now). Enabling it on other platforms (in combination with the
GNUStep Objective-C run time), should simply be a matter of adding
the right {$linklib xxx} statement to rtl/inc/blockrtl.pp file, adding
that file to Makefile.fpc for that platform and adding that platform
to the compiler/systems.systems_blocks_supported set
git-svn-id: branches/blocks@28232 -
