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Tcl Rethrow Error


Specification I propose the following two commands be added to Tcl: throw command. This has the advantage of being a minimalistic extension of the current system & it will be immediately familiar to anyone who has programmed in any mainstream (& also some non-mainstream) This command takes one mandatory argument, the error message; when invoked, it generates an error condition and terminates execution. The message is optional, and is the same as that issued by the catch command, error -code error "message" An instance of throw with no arguments can be used within a have a peek here

alarm can be used in conjunction with signal to generate timeouts. This TIP proposes adding a try/catch command to the Tcl core (or C based Tcl library). Exceptions themselves were a crazy new idea at some point. — Reply to this email directly or view it on GitHub. The next time that you encounter an error as you browse the web, instantly prevent it from getting worse by doing the right thing instead of panicking.

Tcl Error Handling

in the same manner as upvar. And until now Julia has gotten this very right. From what I understood is that your are trying to distinguish between “exceptional” exceptions and “unexceptional” exceptions and I don’t know if that is a good idea.

To actually solve the problem, whether an error is caught must depend, not only on the throw and catch sites, but also on the stack between them. Having a "throws" annotation is essentially saying "throwing this error is part of the official API of this function". The main problem is either a recent change of the software of hardware on your personal computer. Errorinfo Tcl I should probably try out adding these annotations for something like that and see how it goes.

So, where you place your catch statements matter. Tcl Error Code tcl stack-trace share|improve this question edited Feb 5 '10 at 17:13 Trey Jackson 60.4k8151191 asked Feb 3 '10 at 17:02 ls. 125210 add a comment| 3 Answers 3 active oldest votes For me this is kind of the switch clause in C++ where my initial expectation is not a default fallthrough. http://www.tcl.tk/cgi-bin/tct/tip/89.html This wiki page shows how.

What is Tk? Tcl Try Trap I just miss to catch specific exceptions as its available in most other languages that have this. I am all for putting more context into exceptions. If the type throwed is based on the 'exit' type, and is not catched on the current frame, emit a warning.

Tcl Error Code

How can I get the detailed stack trace like above? This is when there is a debate whether all exceptions should be handled (because they are supposed to be errors to handle correctly!), or should be left free to the programmer Tcl Error Handling arg ... Tcl Throw Example 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

e.g. http://colinmeldrum.com/tcl-error/tcl-error-f5.html Here's a motivating scenario: let's say you implement a new kind of AbstractVector – say a kind of sparse vector or something – let's call it SpArray. The body argument to catch is a Tcl script, which catch executes. Is ok to have boxes of raw chicken stacked on top of each other Will Panharmonicon entering the battlefield duplicate ETBs it triggers? Tcl Warning

Only when you decide that something like BoundsErrors or KeyError is part of the official interface of AbstractArray or Associative would you put throws BoundsErrors and throws KeyError annotations on function This is almost absurdly unwieldy. I just think these should be rare. http://colinmeldrum.com/tcl-error/tcl-last-error.html Clear intention, with compiler-assisted warnings.

IMO isa(err, BazError) ... Tcl Try Catch Example When writing catch err::BoundsError I want to catch every occurrence of a BoundsError. Also as Stefan mentions himself throws annotation (& the checked exceptions that go with it) in method definitions in Java have not been a success and I am on of those

First of all: in every programming language I know (& I know a bunch of them), system provided exceptions usually just have a message as a field.

function get_token() if rand() > 0.2 error("Busy") end if rand() > 0.8 error("Throttle") end if rand() > 0.9 error("Crash") end return "12345" end # Implementation of retry macro with_retry_limit(max::Integer, try_expr::Expr) @assert The uplevel command executes arg ... This example would be quite bit more verbose without the convenience macros. @repeat 4 try return http_attempt(request) catch e @delay_retry if typeof(e) == UVError end @delay_retry if http_status(e) < 200 && Tcl Error Codes People will use the isa and rethrow way if they want the standard use of exception.

You might think that the solution is to use file exists first, but open can fail for many other reasons (improper permissions, etc). and @ignore if... catch ... http://colinmeldrum.com/tcl-error/tcl-tk-error.html In my opinion exceptions are complicated enough so that it is a big plus if the implementation is simple.

For compatibility, we could allow throw() to still invoke the function throw while throw ErrorType(args...) would be translated to throw(ErrorType(args...)) throws ErrorType This brings up another issue – what scope should But if you're calling code that returns something with a .code field, then you need to filter on the code. Share this:FacebookTwitterEmailRedditPrintLike this:Like Loading... The things I'm trapping are all well-defined and precise.

For example, the Unix signal 15 (SIGTERM) is the canonical signal to terminate a program; it's sent to all processes by the OS when the system is going down, for example. try { set web_user [create_aws_iam_user $aws $region-web-user] } trap EntityAlreadyExists {} { delete_aws_iam_user_credentials $aws $region-web-user set web_user [create_aws_iam_user_credentials $aws $region-web-user] } retry count 4 { set res [aws_sqs $aws CreateQueue QueueName but we think it would be better if you had written ..." :-) Just kidding. How to write an effective but very gentle reminder email to supervisor to check the Manuscript?

It would not be the most natural syntax, so that people don't use it without enough reflection, but it wouldn't be completely ugly either, like catchall e::BazError. I also think proper exception handling is a bit [too much] overdue. to match your example for test1, if you redefined three as follows: proc three {} { catch {four} puts $::errorInfo } And you evaluated if {[catch {one}]} { puts "Found an to work around bugs in the code you call when the author forgot to add the throws BazError annotation, or do perform some debugging.

Viral Shah said in a separate conversation "The short answer to your question is yes, it is easy to do retry with Julia’s macros". The stack will be unwound until the error is trapped by a suitable catch or try command. The alternative is that all of the code is dominated by deciding what error information needs to be passed back up the stack and how far. catch e @ignore if isa(e, EntityAlreadyExistsError) end @delay_retry if isa(e, NetworkTimeoutError) end end Fine grained exception filtering is important.