[Coco] DEF USR and strings?

[Allen Huffman]

I could have swore I saw someone post (maybe on Facebook) that they realized the DEF USR could accept a string parameter. I had only known to use it like this:

A$=“STRING”
X=USR0(VARPTR(A$))

I went to try it today and it gives me a ?TM ERROR

I checked the Unravelled listing and it looks like it wants to handle strings:

* PROCESS A USR CALL
L892C	BSR	L891C	GET STORAGE LOC OF EXEC ADDRESS FOR USR N
	LDX	,X	* GET EXEC ADDRESS AND
	PSHS	X	* PUSH IT ONTO STACK
	JSR	>LB262	SYNTAX CHECK FOR ‘(‘ & EVALUATE EXPR
	LDX	#FP0EXP	POINT X TO FPA0
	LDA	VALTYP	GET VARIABLE TYPE
	BEQ	L8943	BRANCH IF NUMERIC, STRING IF <> 0
	JSR	>LB657	GET LENGTH & ADDRESS OF STRING VARIABLE
	LDX	FPA0+2	GET POINTER TO STRING DESCRIPTOR
	LDA	VALTYP	GET VARIABLE TYPE
L8943	RTS	JUMP	TO USR ROUTINE (PSHS X ABOVE)

It looks like BEQ L8943 is where it goes if numeric, else it continues and gets the length and address of the string variable and continues.

What is the syntax to make this work?

		— A