R devel - Aug 2020 - trace creates object in base namespace if called on function argument

Dear R-devel,

I don't think this is expected :

foo <- function() "hello"
trace2 <- function(fun) trace(fun, quote(print("!!!")))
base::fun
# Object with tracing code, class "functionWithTrace"
# Original definition:
# function() "hello"
#
# ## (to see the tracing code, look at body(object))

`untrace()` has the same behavior.

This is inconsistent with how debug works :

foo <- function() "hello"
debug2 <- function(fun) debug(fun)
debug2(foo)
isdebugged(foo)
# [1] TRUE

This can be worked around by defining :

trace2 <- function(fun) eval.parent(substitute(trace(fun,
quote(print("!!!")))

but I believe the current behavior is undesired and it'd be better to make
it behave as `debug()`, or to throw an error.

Best,

Antoine

	[[alternative HTML version deleted]]

Apologies there is one line missing in my last email, the code should be :

foo <- function() "hello"
trace2 <- function(fun) trace(fun, quote(print("!!!")))
trace2(foo) # <- THIS LINE WAS MISSING
base::fun

Best,

Antoine

Le mar. 25 ao?t 2020 ? 22:02, Antoine Fabri <antoine.fabri at gmail.com> a
?crit :
> Dear R-devel,
>
> I don't think this is expected :
>
> foo <- function() "hello"
> trace2 <- function(fun) trace(fun, quote(print("!!!")))
> base::fun
> # Object with tracing code, class "functionWithTrace"
> # Original definition:
> # function() "hello"
> #
> # ## (to see the tracing code, look at body(object))
>
> `untrace()` has the same behavior.
>
> This is inconsistent with how debug works :
>
> foo <- function() "hello"
> debug2 <- function(fun) debug(fun)
> debug2(foo)
> isdebugged(foo)
> # [1] TRUE
>
> This can be worked around by defining :
>
> trace2 <- function(fun) eval.parent(substitute(trace(fun,
> quote(print("!!!")))
>
> but I believe the current behavior is undesired and it'd be better to
make
> it behave as `debug()`, or to throw an error.
>
> Best,
>
> Antoine
>
	[[alternative HTML version deleted]]

Please note that this is documented in ?trace. "fun" is matched to
what,
it is a _name_ of the function to be traced, which is traced in the 
top-level environment. I don't know why it was designed this way, but it 
is documented in detail, and hence the expected behavior.

Debugging is often, and also in R, implemented in the core. Tracing is 
implemented on top without specific support, it thus cannot do some 
things debugging can do.

Tomas


On 8/26/20 3:31 AM, Antoine Fabri wrote:
> Apologies there is one line missing in my last email, the code should be :
>
> foo <- function() "hello"
> trace2 <- function(fun) trace(fun, quote(print("!!!")))
> trace2(foo) # <- THIS LINE WAS MISSING
> base::fun
>
> Best,
>
> Antoine
>
> Le mar. 25 ao?t 2020 ? 22:02, Antoine Fabri <antoine.fabri at
gmail.com> a
> ?crit :
>
>> Dear R-devel,
>>
>> I don't think this is expected :
>>
>> foo <- function() "hello"
>> trace2 <- function(fun) trace(fun, quote(print("!!!")))
>> base::fun
>> # Object with tracing code, class "functionWithTrace"
>> # Original definition:
>> # function() "hello"
>> #
>> # ## (to see the tracing code, look at body(object))
>>
>> `untrace()` has the same behavior.
>>
>> This is inconsistent with how debug works :
>>
>> foo <- function() "hello"
>> debug2 <- function(fun) debug(fun)
>> debug2(foo)
>> isdebugged(foo)
>> # [1] TRUE
>>
>> This can be worked around by defining :
>>
>> trace2 <- function(fun) eval.parent(substitute(trace(fun,
>> quote(print("!!!")))
>>
>> but I believe the current behavior is undesired and it'd be better
to make
>> it behave as `debug()`, or to throw an error.
>>
>> Best,
>>
>> Antoine
>>
> 	[[alternative HTML version deleted]]
>
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