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Tcl File Error Handling

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Tcl specifies two entries that are always defined in the dictionary: -code and -level. code: if [catch {set fd [open $filename] } errmsg] { error "Unable to open the file: $filename on Primary Server \n $errmsg" set filename $httpsvr2$textfile if [catch {set fd [open $filename] Then in a "try" block, you can test for the different types of error conditions separately and handle them in different ways. (My complaint about Java is that there seems to Description editcatch is used to intercept the return code from the evaluation of script, which otherwise would be used by the interpreter to decide how to proceed: Whether an error occurred, http://colinmeldrum.com/tcl-error/tcl-error-handling.html

it's possible that a non-error situation in the script can give the return value of [catch] a value other than 0 for example, if you simply use a [return] to exit This approach described here could be described as an expection handling system as it tries to perform an operation and traps if a failure occurs, rather than trying to predict the Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the Synopsis editcatch script ?messageVarName? ?optionsVarName?

Tcl Error Handling

The syntax for each of these commands is shown below. The definitive method is seen as KBK's contribution to the exec page.LES: or should one rather follow advice given at exec and error information? Here's the program above, enhanced to catch any errors:
puts -nonewline "please enter a number: "
flush stdout
gets stdin value
if {[catch {set doubled [expr An example for simple error handling is shown below − #!/usr/bin/tclsh proc Div {a b} { if {$b == 0} { error "Error generated by error" "Info String for error" 401

You can turn off the stack trace with the -n argument to the megatcl (or Extended Tcl) interpreter: $ megatcl -n -c "while 1 {if 1 {set foo}}" Error: can't read The alarm Command alarm seconds The Extended Tcl alarm command arranges for the kernel to send your process a SIGALRM (signal 14) in seconds seconds (this is a floating point value, Why is this file name truncated in Nautilus? Tcl Catch Exec catch script ?varName?

The catch command calls the Tcl interpreter recursively to execute script, and always returns without raising an error, regardless of any errors that might occur while executing script. Tcl Try Catch Example arg ... The programmer can then decide what to do about those errors and act accordingly, instead of having the whole application come to a halt. timeout uses the SIGALRM alarm signal.

If it is 0, it's because the file couldn't be opened on any of the servers, so I will just treat the call as if it's a working (non-holiday) day. Tcl Error Command If script raises an error, catch will return a non-zero integer value corresponding to the exceptional return code returned by evaluation of script. Note that unwindProtect doesn't catch the error, it passes it on after executing protected. Documentation edithttp://www.tcl.tk/man/tcl/TclCmd/catch.htmOfficial reference.TIP 90, Enable return -code in Control Structure ProcsIncludes a good description of the operation of catch.

Tcl Try Catch Example

Will this work, or do I need to change on error to on error {result options}? anchor See Also editbreakcontinuereturnerrormagic nameserrorCodeerrorInfoTcl performance: catch vs. Tcl Error Handling See the timeout command below. Tcl Throw Error Not the answer you're looking for?

From glass painting to Tcl and Lua courses.Tcl collections - lists, dicts and arrayTcl - apparently odd behaviour of string trimleftMultiple buttons calling the same proc in wish (tcl/tk)Adding Expect on navigate here more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed So in C, you have to add checks for everything that might go wrong; in Tcl, you only need to treat errors if you can express it better than Tcl already For example, use the following to detect that an attempt to put a record into the database failed because the key already existed: % berkdb open -create -btree a.db db0 % Tcl Errorinfo

Getting Tcl/Tk Getting help Learning Tcl Tcl Dev Xchange About the Wiki Community Advocacy Conferences Chat, news, lists History Humor People Tcl websites Reference Companies Getting help Online books Online tutorials Are two standard normal random variables always independent? In either case, a message will be placed in errorInfo, and the proc will generate an error. http://colinmeldrum.com/tcl-error/tcl-error-handling-example.html If an error is returned while opening the file, I want to try to use a secondary backup server.

The break condition, generated by the break command. Try Catch Block In Tcl Firstly, with correct data:
earth-wind-and-fire:~/jul05 grahamellis$ wish ifcat
please enter a number: 17
Succeeded and result is 34
application continues ...
earth-wind-and-fire:~/jul05 grahamellis$
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When the return code from the script is 0 (TCL_OK), the value stored in resultVarName is the value returned from script.

Join them; it only takes a minute: Sign up TCL open file and check for error up vote 2 down vote favorite I am programming TCL for Cisco TCL/IVR inside voice more hot questions question feed default about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation Tcl commands often generate errors in cases where, in most programming languages, a subroutine would return a special value that would have to checked for. Tcl If Catch The value of the -errorline entry is an integer indicating which line of script was being evaluated when the error occurred.

Tcl has no throw command, but still you can call it. If an error occurs deep within several levels of procedure invocations, the stack trace can be very long. Error syntax error message info code In the above error command syntax, message is the error message, info is set in the global variable errorInfo and code is set in the this contact form Getting Tcl/Tk Getting help Learning Tcl Tcl Dev Xchange About the Wiki Community Advocacy Conferences Chat, news, lists History Humor People Tcl websites Reference Companies Getting help Online books Online tutorials

This command executes the Tcl script code, returning its result if there is no error. The problem in that case is that the caller isn't obeying the interface contract, not that the implementation has gone wrong.RS 2001-11-21: In C, errors are something you loathe and try more hot questions question feed lang-sh about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation Browse other questions tagged shell-script files expect error-handling tcl or ask your own question.

For this you need catch: if [catch {open $file r} result] { # error! Some New Control Structures Here are some example of new control structures. if ![regexp {^[0-9]+$} $num] { error "num must be numeric" } error takes two optional arguments which we will discuss later. See the try command.

In theory, we could use different return codes to signal different types of error, but in practice this is hardly ever used.I think it is extreme parochialism to state "it's a error message ?info? ?code? Description editGenerates an error with the specified message. Browse other questions tagged tcl or ask your own question.

The catch command returns 0 if there is no error, and 1 if there is an error. The catch Command catch body ?var?