在错误和 catch 命令的帮助下提供了Tcl中的错误处理.每个命令的语法如下所示.
error message info code
在上面的错误命令语法中,message是错误消息,info在全局变量errorInfo中设置,代码在全局变量errorCode中设置.
catch script resultVarName
在上面的catch命令语法中,script是要执行的代码,resultVarName是保存错误或结果的变量.如果没有错误,catch命令返回0,如果有错误,则返回1.
简单错误处理的示例如下所示 :
#!/usr/bin/tclsh proc Div {a b} { if {$b == 0} { error "Error generated by error" "Info String for error" 401 } else { return [expr $a/$b] } } if {[catch {puts "Result = [Div 10 0]"} errmsg]} { puts "ErrorMsg: $errmsg" puts "ErrorCode: $errorCode" puts "ErrorInfo:\n$errorInfo\n" } if {[catch {puts "Result = [Div 10 2]"} errmsg]} { puts "ErrorMsg: $errmsg" puts "ErrorCode: $errorCode" puts "ErrorInfo:\n$errorInfo\n" }
执行上述代码时,会生成f ollowing结果 :
ErrorMsg: Error generated by error ErrorCode: 401 ErrorInfo: Info String for error (procedure "Div" line 1) invoked from within "Div 10 0" Result = 5
正如您在上面的示例中所看到的,我们可以创建自己的自定义错误消息.类似地,可以捕获由Tcl生成的错误.示例如下所示 :
#!/usr/bin/tclsh catch {set file [open myNonexistingfile.txt]} result puts "ErrorMsg: $result" puts "ErrorCode: $errorCode" puts "ErrorInfo:\n$errorInfo\n"
执行上述代码时,会产生以下结果 :
ErrorMsg: couldn't open "myNonexistingfile.txt": no such file or directory ErrorCode: POSIX ENOENT {no such file or directory} ErrorInfo: couldn't open "myNonexistingfile.txt": no such file or directory while executing "open myNonexistingfile.txt"