Nested macro silliness bug:

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bitRAKE

Joined: 21 Jul 2003
Posts: 4061
Location: vpcmpistri

bitRAKE 05 Jul 2013, 10:25

The following code silently errors:

Code:

macro T [A] {
  macro T [B] \{
    macro T [C] \\{
      macro T [D] \\\{
        display \\\`D
      \\\}
      irp X,C \\\{ T X \\\}
    \\}
    irp Y,B \\{ T Y \\}
  \}
  irp Z,A \{ T Z \}
}

T 0,<1,0>,<2,<0,1>>,<3,<<1,0>,2>>

Code:

01020131

Whereas this code works as expected:

Code:

macro T [A] {
  macro T [B] \{
    macro T [C] \\{
      irp X,C \\\{
        display \\\`X
      \\\}
    \\}
    irp Y,B \\{ T Y \\}
  \}
  irp Z,A \{ T Z \}
}

T 0,<1,0>,<2,<0,1>>,<3,<<1,0>,2>>

Code:

0102013102

Maybe it's running out of stack space and isn't catching it?

I'm only figuring this because nesting another level does report a stack error.

_________________
¯\(°_o)/¯ “languages are not safe - uses can be” Bjarne Stroustrup

05 Jul 2013, 10:25

l_inc

Joined: 23 Oct 2009
Posts: 881

l_inc 05 Jul 2013, 14:37

bitRAKE

Quote:

The following code silently errors:

There's no error there. The example is a little convoluted, so I assume you outsmarted yourself.

Basically, you're running irp for each argument (because no common directive is used). With the very last argument the most outer irp is called like this:

Code:

irp Z,3,<<1,0>,2>{T Z}

With the first iteration you invoke on the same level redefined T macro. But because the macro redefines itself, when invoked, the second iteration uses the most internal T macro, which contains the display directive only. Thus the second (and therefore the last) iteration of the last irp invokes the most inner redefinition:
T<1,0>,2 =>
display '1',0
display '2'
As you terminated the output with non-stringified 0, no further output is displayed.

_________________
Faith is a superposition of knowledge and fallacy

05 Jul 2013, 14:37

bitRAKE

Joined: 21 Jul 2003
Posts: 4061
Location: vpcmpistri

bitRAKE 05 Jul 2013, 16:35

l_inc wrote:

The example is a little convoluted, so I assume you outsmarted yourself.

Thank you, by renaming the internal macros - it also fixes the stack overflow, when I increase the nesting. (Suppose I should be using purge, too.)

_________________
¯\(°_o)/¯ “languages are not safe - uses can be” Bjarne Stroustrup

05 Jul 2013, 16:35

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