RE: [sv-bc] Clarification on space stripping for passed arguments in macros

I uploaded a new version of the proposal which has some examples of when
white space stripping occurs and when not.
 
Shalom


________________________________

	From: owner-sv-bc@server.eda.org
[mailto:owner-sv-bc@server.eda.org] On Behalf Of Bresticker, Shalom
	Sent: Saturday, August 04, 2007 11:24 PM
	To: Alsop, Thomas R; sv-bc@server.eda.org
	Subject: RE: [sv-bc] Clarification on space stripping for passed
arguments in macros
	
	
	Hi, Tom.


________________________________

		From: owner-sv-bc@server.eda.org
[mailto:owner-sv-bc@server.eda.org] On Behalf Of Alsop, Thomas R
		Sent: Friday, August 03, 2007 9:06 PM
		To: sv-bc@server.eda.org
		Subject: [sv-bc] Clarification on space stripping for
passed arguments in macros
		
		

		Just one clarification in this mantis item.  Can we add
an example of "White space before and after the arguments shall be
stripped off"  
		[SB]  OK, I will alter at least one of the examples to
show this. I thought I had done so,  but maybe I forgot.

		
		What happens for example of I do this:

		 

		`D(" msg1","msg2 ")

		 

		Note the white space in the arguments.  

		 

		Do I get this? 

		prints "startmsg1msg2end"

		 

		Or this?

		prints "start msg1msg2 end"

		[SB]  The second, because the arguments are the string
literals, each of which is a single token.

		 

		This leads to another question about using quotations to
pass the argument.  Do we ever expect anyone to want to actually pass a
string with a space prefix or suffix?  In which case it would be nice to
let them do this by explicitly using quotations and making this "space
stripping" enhancement only apply to non-quoted arguments.  So perhaps
this can be clarified as well.  If I have a macro call like this:

		 

		`D(msg1,msg2)

		 

		I assume this is the same as this:

		 

		`D("msg1","msg2")
		[SB] No, it is not, because the second passes the
quotation marks as well. Changing this would break back-compatibility. 

		 

		But what about calls like this:

		 

		`D( msg1,msg2 )

		 

		Would this example be equivalent to this?

		 

		`D(" msg1","msg2 ")
		[SB] No, for the same reason.

		 

		Regards,

		Shalom 

		 

		Thanks, -Tom

		 

		 

		Mantis 1957

		A macro actual argument may be empty

		In P1800-2008/D3a. Section 21.5.1, 

		CHANGE

		To use a macro defined with arguments, the name of the
text macro shall be followed by a list of actual arguments in
parentheses, separated by commas. White space shall be allowed between
the text macro name and the left parenthesis. The number of actual
arguments shall match the number of formal arguments.

		TO

		To use a macro defined with arguments, the name of the
text macro shall be followed by a list of actual arguments in
parentheses, separated by commas. White space shall be allowed between
the text macro name and the left parenthesis. White space before and
after the arguments shall be stripped off before argument substitution
into the macro text. 

		 

		The number of actual arguments shall match the number of
formal arguments. However,  an actual argument may be empty or white
space only, in which case the formal argument is substituted by nothing.
Commas must still be used to maintain the correct number of arguments.

		 

		Example:

		`define D(x,y) initial $display("start", x , y, "end");

		 

		`D("msg1","msg2") // prints "startmsg1msg2end"

		`D("msg1", )      // prints "startmsg1 end"

		`D(,"msg2")       // prints "start msg2end"

		`D(,)             // prints "start  end"

		`D("msg1")        // illegal, only one argument

		`D()              // illegal, only one empty argument

		 

		 


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