Thread overview
[Issue 4720] New: contracts don't work on function definitions
Aug 24, 2010
Trass3r
Aug 24, 2010
Don
August 24, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4720

           Summary: contracts don't work on function definitions
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: mrmocool@gmx.de


--- Comment #0 from Trass3r <mrmocool@gmx.de> 2010-08-24 05:23:06 PDT ---
The Matlab C headers provide some kind of hand-crafted contracts by defining extra functions with suffix "_d" that check all the arguments and then detouring the calls to the original functions via the preprocessor (#define foo foo_d)

I tried to leverage D's built-in contract programming but it doesn't work:

module externcontracts;
import externcontracts2;
void foo(int a) in {assert(a>=0);}

module externcontracts2;
void foo(int a){}

yields:
externcontracts.d(3): Error: function externcontracts.foo in and out contracts
require function body
resp.
externcontracts.d(3): missing body { ... } after in or out
if you put a ';' after the in{} block


Note that this is exactly the same syntax as for interface contracts.

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August 24, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4720


Don <clugdbug@yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug@yahoo.com.au
           Severity|normal                      |enhancement


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February 08, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4720


Andrei Alexandrescu <andrei@erdani.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrei@erdani.com


--- Comment #1 from Andrei Alexandrescu <andrei@erdani.com> 2013-02-08 05:07:16 PST ---
What is the expected use and effect of the code show? (Not sure I'm getting it.) With or without contracts, externcontracts.foo and externcontracts2.foo are distinct functions, so automatic forwarding from one another won't happen.

One obvious workaround would be:

module externcontracts;
import externcontracts2;
void foo(int a) in {assert(a>=0);} { return externcontracts2.foo(a); }

which may be automated in a number of ways (introspection, mixin etc).

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