In Java you can use try with resources to open a file (resource) and
you do not have to take care of the closing of the file. Does tcl has
something like that?

If not is the following a good way to simulate it partly. (I count on
it that there will be no problem with the read.)
if {[catch {set speedtestFP [open ${speedtestCmd} RDONLY]} openError]} {
puts stderr "Could not start speedtest (${openError})"
return
}
for {set i 0} {$i < 1} {incr i} {
gets ${speedtestFP} pingLine
if {[regexp ${checkPing} ${pingLine} -> ping] != 1} {
puts stderr "Could not get the ping value (${pingLine})"
break
}
gets ${speedtestFP} downloadLine
if {[regexp ${checkDownload} ${downloadLine} -> download] != 1} {
puts stderr "Could not get the download value (${downloadLine})"
break
}
gets ${speedtestFP} uploadLine
if {[regexp ${checkUpload} ${uploadLine} -> upload] != 1} {
puts stderr "Could not get the upload value (${uploadLine})"
break
}
showMessage "${ping} ${download} ${upload}" True
storeSpeedtestDo ${ping} ${download} ${upload} \
${::speedtestSleep} ${::intervalSpeedtest}
}
if {[catch {close ${speedtestFP}} closeError]} {
puts stderr "Could not close speedtest (${closeError})"
return
}

In Java I could just use a return, but I can not leave an open
file-pointer.

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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* Cecil Westerhof <[email protected]>
| In Java you can use try with resources to open a file (resource) and
| you do not have to take care of the closing of the file. Does tcl has
| something like that?

Check the TCL 'try' command:

https://www.tcl.tk/man/tcl/TclCmd/try.html

While it does not automagically close the file handle, it allows to
close it in the 'finally' clause, no matter what. See the 'Examples'
section in the above manpage.

HTH
R'

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Ralf Fassel <[email protected]> writes:

* Cecil Westerhof <[email protected]>
| In Java you can use try with resources to open a file (resource) and
| you do not have to take care of the closing of the file. Does tcl has
| something like that?

Check the TCL 'try' command:

https://www.tcl.tk/man/tcl/TclCmd/try.html

While it does not automagically close the file handle, it allows to
close it in the 'finally' clause, no matter what. See the 'Examples'
section in the above manpage.

Yes that would work. I have:
proc tryWithFinally {} {
try {
puts "I am in the try"
return
} finally {
puts "Got in the finally"
}
}

tryWithFinally

and I get:
I am in the try
Got in the finally

It does not work with an exit, but I do not mind that.
(At the moment.)


But I have to look further into it. I tried simulating an error with
an immediate return. Then I get:
child process exited abnormally

Probably because I close the process before it is finished.

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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On 12/9/21 12:31 AM, Cecil Westerhof wrote:

In Java you can use try with resources to open a file (resource) and
you do not have to take care of the closing of the file. Does tcl has something like that?

There is a package "defer" of tcllib, doing for this purpose.

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On Wednesday, December 8, 2021 at 9:14:05 PM UTC+1, Cecil Westerhof wrote:

It does not work with an exit, but I do not mind that.
(At the moment.)

Side-note: you can rename exit to create your own version of it (and your new exit is invoked even if it is not called explicitly)

expect:/tmp$ namespace eval my {}
expect:/tmp$ rename exit ::my::exit
expect:/tmp$ proc exit args {puts gotcha; tailcall ::my::exit $args} expect:/tmp$ ^C
gotcha

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On Wed, 08 Dec 2021 21:08:23 +0100
Cecil Westerhof <[email protected]> wrote:

Yes that would work. I have:
proc tryWithFinally {} {
try {
puts "I am in the try"
return
} finally {
puts "Got in the finally"
}
}

tryWithFinally

and I get:
I am in the try
Got in the finally

It does not work with an exit, but I do not mind that.
(At the moment.)

it works with [tailcall]


$ tclsh
% proc tryWithFinally {} {
try {
puts "I am in the try"
tailcall exit
} finally {
puts "Got in the finally"
}
}
% tryWithFinally
I am in the try
Got in the finally
$


--
Emiliano Gavilan

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* Emiliano Gavilan <[email protected]>
| $ tclsh
| % proc tryWithFinally {} {
| try {
| puts "I am in the try"
| tailcall exit
| } finally {
| puts "Got in the finally"
| }
| }

Man tailcall(n) says:

DESCRIPTION
The tailcall command replaces the currently executing procedure,
lambda application, or method with another command.
[...]
This command may not be invoked from within an uplevel into a
procedure or inside a catch inside a procedure or lambda.

I read that as "don't use tailcall inside catch", like this

# dont:
catch {
tailcall ...
}

Is it ok to use 'tailcall' in 'try', or is 'try' missing as "don't do
this" in the documentation?

R'

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