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March 15, 2009 [Issue 2733] New: Unclear semantics of template value parameters | ||||
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http://d.puremagic.com/issues/show_bug.cgi?id=2733 Summary: Unclear semantics of template value parameters Product: D Version: 2.025 Platform: PC OS/Version: Windows Status: NEW Keywords: accepts-invalid, spec Severity: normal Priority: P2 Component: DMD AssignedTo: bugzilla@digitalmars.com ReportedBy: samukha@voliacable.com The following code compiles but the generated binary is not correct. import std.stdio; void foo(string s)() { writefln(s); } void main() { string s = "test"; foo!(s); } ---- Prints nothing. In less trivial cases, passing non-const arguments to value parameters causes data corruption/access violations. It is not defined whether the argument should be passed by alias or the code should fail to compile complaining about the argument not being evaluatable at compile time. -- |
April 01, 2009 [Issue 2733] Unclear semantics of template value parameters | ||||
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Posted in reply to d-bugmail | http://d.puremagic.com/issues/show_bug.cgi?id=2733 smjg@iname.com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |smjg@iname.com ------- Comment #1 from smjg@iname.com 2009-04-01 04:53 ------- Non-alias template arguments are, by definition, compile-time constants. s isn't a compile-time constant - it's a mutable reference to immutable data. So this shouldn't compile. -- |
April 01, 2009 [Issue 2733] Unclear semantics of template value parameters | ||||
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Posted in reply to d-bugmail | http://d.puremagic.com/issues/show_bug.cgi?id=2733 ------- Comment #2 from samukha@voliacable.com 2009-04-01 05:13 ------- I'm not that sure anymore. Actually, I wouldn't mind if they were passed by alias. Then, I could write simply template foo(string s) {} instead of template foo(alias s) if (isString!(s)) {} If I want to restrict template arguments to statically known values, I can use a isCompileTime constraint template foo(string s) if (isCompileTime!(s)) { } -- |
April 01, 2009 [Issue 2733] Unclear semantics of template value parameters | ||||
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Posted in reply to d-bugmail | http://d.puremagic.com/issues/show_bug.cgi?id=2733 ------- Comment #3 from smjg@iname.com 2009-04-01 07:05 ------- (In reply to comment #2) > If I want to restrict template arguments to statically known values, I can use a isCompileTime constraint Templates with non-alias parameters are instantiated by value at compile-time in the first place. What you're proposing would be a radical change to this. You could try defining that such a template may be instantiated either by value or by alias. However, this is effectively creating two mutually incompatible templates, and it can be confusing to try to work out which is being instantiated. I can't think of a practical use case for passing a string by alias in a function template, but I'm guessing there's a use for it in templates of some kinds. The question is whether there are enough use cases for syntactic sugar to be worthwhile, but it could look something like template foo(string alias s) .... -- |
June 28, 2009 [Issue 2733] Unclear semantics of template value parameters | ||||
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Posted in reply to d-bugmail | http://d.puremagic.com/issues/show_bug.cgi?id=2733 Christian Kamm <kamm-removethis@incasoftware.de> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |kamm-removethis@incasoftwar | |e.de Version|2.025 |1.045 --- Comment #4 from Christian Kamm <kamm-removethis@incasoftware.de> 2009-06-28 00:14:00 PDT --- I changed the version to a D1 one as it is also accepts-invalid there. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
January 23, 2012 [Issue 2733] Unclear semantics of template value parameters | ||||
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Posted in reply to d-bugmail | http://d.puremagic.com/issues/show_bug.cgi?id=2733 Walter Bright <bugzilla@digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords|spec | CC| |bugzilla@digitalmars.com --- Comment #5 from Walter Bright <bugzilla@digitalmars.com> 2012-01-23 00:28:38 PST --- Not a spec issue - it's a D1 only bug where a template value parameter that is not a compile-time constant is allowed. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
January 30, 2012 [Issue 2733] Unclear semantics of template value parameters | ||||
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Posted in reply to d-bugmail | http://d.puremagic.com/issues/show_bug.cgi?id=2733 yebblies <yebblies@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED CC| |yebblies@gmail.com Resolution| |DUPLICATE --- Comment #6 from yebblies <yebblies@gmail.com> 2012-01-30 17:25:10 EST --- *** This issue has been marked as a duplicate of issue 2257 *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
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