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Comment:Revision through web from Harald Oehlmann <[email protected]> Formatting
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SHA3-256: 500787b368be25c1f5b894891eaffc82b1e40c33792a037447edf0ad247bf572
User & Date: tclhttpd 2014-04-24 20:48:44.000
Context
2014-04-24
20:51
Revision through web from Harald Oehlmann <[email protected]> check-in: 673e95e709 user: tclhttpd tags: trunk
20:48
Revision through web from Harald Oehlmann <[email protected]> Formatting check-in: 500787b368 user: tclhttpd tags: trunk
20:46
Revision through web from Harald Oehlmann <[email protected]> Added example and perspective for fconfigure -lasterror corresponding function. check-in: e1aea0a918 user: tclhttpd tags: trunk
Changes
Unified Diff Ignore Whitespace Patch
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TIP:            428
Title:          Produce Error Dictionary from 'fconfigure -error'
Version:        $Revision: 1.5 $
Author:         Harald Oehlmann <[email protected]>
Author:         Harald Oehlmann <[email protected]>
State:          Draft
Type:           Project
Vote:           Pending
Created:        16-Mar-2014
Post-History:   



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TIP:            428
Title:          Produce Error Dictionary from 'fconfigure -error'
Version:        $Revision: 1.6 $
Author:         Harald Oehlmann <[email protected]>
Author:         Harald Oehlmann <[email protected]>
State:          Draft
Type:           Project
Vote:           Pending
Created:        16-Mar-2014
Post-History:
︙︙
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The following example demonstrates the use.
It checks for an error, closes the channel on error and propages the error to the caller:

|if {[catch {fconfigure $h -throwerror} e d]} {
|    catch {close $h}
|    puts "$h:$d"
|    # -> returns "connection refused:-code 1 -level 0 -errorcode {POSIX
ECONNREFUSED {connection refused}} -errorinfo {couldn't open socket:
connection refused"
|    # fail with the error
|    unset d -level
|    return -options $d $e
|}

~ Alternatives

Revision 1.2 of this TIP proposed to return an error dict like '''d''' in '''catch {code} e d'''.
This approach had the following issues:

   * A new member must be invented to include the error message

   * The standard error mechanisms like '''catch''' may not be used to detect the error occurence. Instead, a comparison of a dict member must be done.

~ Further perspectives

Here are the fconfigure options with similar functionality:

 * '''fconfigure -lasterror''': serial, win only: returns something like the
second component of an errorCode list: '''lindex $::errorCode 1'''

 > * channel must not be closed, serial errors may be temporary.

 * '''fconfigure -error''': socket, all platforms: returns an error message

 > * channel must be closed, no way to recover (with tcp).

 > * '''fconfigure -throwerror''' may also be implemented for the windows serial driver.

~ Implementation

Implementation might be available soon.

~ Copyright

This document has been placed in the public domain.








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The following example demonstrates the use.
It checks for an error, closes the channel on error and propages the error to the caller:

|if {[catch {fconfigure $h -throwerror} e d]} {
|    catch {close $h}
|    puts "$h:$d"
|    # -> returns "connection refused:-code 1 -level 0 -errorcode {POSIX ECONNREFUSED {connection refused}} -errorinfo {couldn't open socket: connection refused"


|    # fail with the error
|    unset d -level
|    return -options $d $e
|}

~ Alternatives

Revision 1.2 of this TIP proposed to return an error dict like '''d''' in '''catch {code} e d'''.
This approach had the following issues:

   * A new member must be invented to include the error message

   * The standard error mechanisms like '''catch''' may not be used to detect the error occurence. Instead, a comparison of a dict member must be done.

~ Further perspectives

Here are the fconfigure options with similar functionality:

   * '''fconfigure -lasterror''': serial, win only: returns something like the
second component of an errorCode list: '''lindex $::errorCode 1'''

   > * channel must not be closed, serial errors may be temporary.

   * '''fconfigure -error''': socket, all platforms: returns an error message

   > * channel must be closed, no way to recover (with tcp).

   > * '''fconfigure -throwerror''' may also be implemented for the windows serial driver.

~ Implementation

Implementation might be available soon.

~ Copyright

This document has been placed in the public domain.