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I don't think a development system without C headers is interesting.. Is it really?<BR>
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The transform I apply at times is wherever there is interaction with C code that is described by system-dependent headers, or perhaps even fairly system-independent headers outside the Modula-3 tree, either write wrapper functions for the functionality in the headers (e.g. stat, waitpid), which can be done in a system-independent way, or move the Modula-3<->C transition higher, which is also usually system-independent, e.g. ThreadPThreadC_SetupHandlers.<BR>
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It is either that or clone the headers, which seems like the worse evil.<BR>
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There is always going to be a Modula-3<->C transition, it is just a matter of where it occurs.<BR>
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- Jay<BR><BR>
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CC: m3devel@elegosoft.com<BR>From: hosking@cs.purdue.edu<BR>To: jay.krell@cornell.edu<BR>Subject: Re: [M3devel] declaring a type's existance but not enough to instantiate it?<BR>Date: Mon, 12 Jan 2009 12:32:15 +1100<BR><BR><BR>
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<DIV>Jay, I really think you are bending over backwards too far just to be able to shoe-horn things into C. I *like* having the transpar of C header files expressed in Modula-3, *particularly* for system calls, where you might even be trying to build on a system that does not have the C header files installed, even though the libraries exist and can be linked to. Fundamentally, I think anytime the Modula-3 code is made less transparent you should think hard about what you are doing. The same with the change of constants to variables.</DIV>
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<DIV>I am getting very nervous that the changes you are making are destroying the clarity of the Modula-3 run-time code.</DIV>
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<DIV>In this particular case, you are wanting to use a Modula-3 parameter passing mechanism on something that is not declared in Modula-3. Seems kind of dubious to me. Also, I really don't like the idea of accessing external variables in C.</DIV>
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<DIV>-- Tony</DIV></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></SPAN></DIV></SPAN></DIV><BR>
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<DIV>On 12 Jan 2009, at 11:55, Jay wrote:</DIV><BR class=EC_Apple-interchange-newline>
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<DIV class=EC_hmmessage style="FONT-SIZE: 10pt; FONT-FAMILY: Verdana">I considered ADDRESS.<BR>However I think it still doesn't satisfy.<BR> <BR>I want to be able to do this:<BR> <BR>TYPE Foo_t = something;<BR><* EXTERNAL *> VAR Foo1, Foo2:Foo_t;<BR><* EXTERNAL *> PROCEDURE UseFoo(READONLY (* or VAR *) foo:Foo_t);<BR> <BR>(* Modula-3, not external *)<BR>PROCEDURE x()=<BR>BEGIN<BR> UseFoo(Foo1);<BR> UseFoo(Foo2);<BR>END x;<BR> <BR>AND I want any use of:<BR>VAR Foo3:Foo3_t; (* Modula-3, not external *)<BR><BR>to error. This is sem_t and sigset_t in particular.<BR> <BR>Possibly renaming is the thing.<BR>They used to be declared in Modula-3, system-dependently, but<BR>I moved them to portable C.<BR> <BR>I could remove the types entirely and change UseFoo to take an address,<BR>and declare mask and ackSem to be integers or I guess.<BR><*EXTERNAL> VAR ackSem : RECORD END;<BR> <BR>That would satisfy but I thought it might be nicer to still provide the named<BR>types to refer to the external variables.<BR> <BR> - Jay<BR><BR>
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<BR>From:<SPAN class=EC_Apple-converted-space> </SPAN><A href="mailto:hosking@cs.purdue.edu">hosking@cs.purdue.edu</A><BR>To:<SPAN class=EC_Apple-converted-space> </SPAN><A href="mailto:jay.krell@cornell.edu">jay.krell@cornell.edu</A><BR>Date: Mon, 12 Jan 2009 11:13:00 +1100<BR>CC:<SPAN class=EC_Apple-converted-space> </SPAN><A href="mailto:m3devel@elegosoft.com">m3devel@elegosoft.com</A><BR>Subject: Re: [M3devel] declaring a type's existance but not enough to instantiate it?<BR><BR>What's wrong with using ADDRESS for references to opaque values? If sigset_t is never instantiated in Modula-3, then why do you need it declared there?<BR>
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<DIV>On 12 Jan 2009, at 01:44, Jay wrote:</DIV><BR class=EC_EC_Apple-interchange-newline>
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<DIV class=EC_EC_hmmessage style="FONT-SIZE: 10pt; FONT-FAMILY: Verdana">Is there a way in Modula-3 to declare that a type exists, and there are <*external*> instances of it, without "fully" declaring it, so that no Modula-3 can instantiate it?<BR> <BR>I have done this for sigset_t and sem_t, but they could erroneously be instantiated by Modula-3 and I'd like to remove that ability to mess up so easily.<BR> <BR>(* This type is not declared correctly. It is only instantiated in C code. *)<BR> sigset_t = RECORD END;<BR><BR>(* This type is not declared correctly. It is only instantiated in C code. *)<BR> sem_t = RECORD END;<BR><BR>In C I believe you can do this, like:<BR> typedef struct foo foo_t; <SPAN class=EC_EC_Apple-converted-space> </SPAN><BR> extern foo_t foo; <SPAN class=EC_EC_Apple-converted-space> </SPAN><BR> <BR> void UseFoo(foo_t*);<SPAN class=EC_EC_Apple-converted-space> </SPAN><BR> foo_t* GetFoo(void);<SPAN class=EC_EC_Apple-converted-space> </SPAN><BR> <BR>Thanks,<BR> - Jay<BR><BR><BR><BR></DIV></SPAN></BLOCKQUOTE></DIV><BR></DIV></DIV></SPAN><BR class=EC_Apple-interchange-newline></BLOCKQUOTE></DIV><BR></body>
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