1error(n) Tcl Built-In Commands error(n)
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6
8 error - Generate an error
9
11 error message ?info? ?code?
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16 Returns a TCL_ERROR code, which causes command interpretation to be
17 unwound. Message is a string that is returned to the application to
18 indicate what went wrong.
19 The -errorinfo return option of an interpreter is used to accumulate a
21 stack trace of what was in progress when an error occurred; as nested
22 commands unwind, the Tcl interpreter adds information to the -errorinfo
23 return option. If the info argument is present, it is used to initial‐
24 ize the -errorinfo return options and the first increment of unwind
25 information will not be added by the Tcl interpreter. In other words,
26 the command containing the error command will not appear in the stack
27 trace; in its place will be info. Historically, this feature had been
28 most useful in conjunction with the catch command: if a caught error
29 cannot be handled successfully, info can be used to return a stack
30 trace reflecting the original point of occurrence of the error:
31 catch {...} errMsg
32 set savedInfo $::errorInfo
33 ...
34 error $errMsg $savedInfo
35 When working with Tcl 8.5 or later, the following code should be used
36 instead:
37 catch {...} errMsg options
38 ...
39 return -options $options $errMsg
40 If the code argument is present, then its value is stored in the
42 -errorcode return option. The -errorcode return option is intended to
43 hold a machine-readable description of the error in cases where such
44 information is available; see the return manual page for information on
45 the proper format for this option's value.
46
48 Generate an error if a basic mathematical operation fails:
49 if {1+2 != 3} {
50 error "something is very wrong with addition"
51 }
52
55 catch(n), return(n)
56
59 error
60Tcl error(n)