id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	difficulty
1285	parameterize doesn't restore current-{input,output,error}-port correctly	evhan		"Because {{{current-input-port}}} et al. ignore the {{{convert?}}} and {{{set?}}} arguments that are passed to them when they're called from the expansion of {{{parameterize}}}, their values are not restored properly when the parameterize expression ends.

Specifically, this is because the expansion's before thunk calls these procedures with the {{{convert?}}} argument set to {{{#t}}} and {{{set?}}} set to {{{#f}}} in order to invoke the object's (nonexistent) converter procedure without setting its value, but this has the effect of setting the port's value anyway since the ports don't know about these extra arguments.

{{{
(parameterize ((current-output-port (current-error-port)))
  (current-output-port))
}}}

There may be other parameter-like objects that aren't really parameters that exhibit this problem."	defect	closed	critical	4.11.0	unknown	4.10.x	fixed	parameters, runtime, ports