question: make-parameter and prop:custom-write
Jacob Jozef
Hi
I have a program that runs well with version 7.2, but does not run starting from version 8.0.
I can make the program running on 8.3 by eliminating small parts of the code.
Details:
I have a meta-recursive interpreter that uses structs with prop:custom-write.
It has a trace option showing subexpressions being evaluated and their values.
When the interpreter interprets its own source code with tracing enabled,
the printer given to prop:custom-write must be disabled, of course,
for otherwise an infinite loop occurs (the body of the printer being traced too,
causing the tracer to trace itself)
Therefore I use a parameter that disables tracing within a prop:custom-write printer.
This works fine in 7.2.
However, in 8.3 it does not work. DrRacket closes entirely within a second.
When I change tracing such as to not print values, 8.3 works fine.
Have things been changed with parameters that may cause my problem?
I have seen a name argument has been added to make-parameter,
but that can’t be the problem I think.
If you need more info, I can try to prepare a minimal code that produces the problem,
but this requires some work and probably is not easy.
May be, the brief info in this email is enough for someone to direct me to an answer.
Thanks, Jos
Jacob Jozef
Thanks for your prompt answer.
No problems on 8.3 BC.
If I am well informed CS is the recommended version???
No problems either with 7.9.
Problem starts at 8.0.
Thanks for your offer to look at the full program,
but if possible I want to spare you the trouble.
If you desire so, I can put the code and tests on GitHub.
Thanks again, Jos
From: Sam Tobin-Hochstadt
Sent: viernes, 3 de diciembre de 2021 20:15
To: Jacob Jozef
Cc: Racket Users
Subject: Re: [racket-users] question: make-parameter and prop:custom-write
Lots of things have happened since 7.2 that might be relevant, ranging
from the switch to Chez Scheme as a back end to minor details of
parameters. Have you tried with the BC version of 8.3? Alternatively,
have you tried with any versions in between?
I'd be happy to look at the full code, even without reducing it, if
you're willing to share it.
Sam
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