在 TCL catch 命令中捕获标准输出

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问题描述

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在我的主 tcl 脚本中，我调用了一个包含在 catch 命令中的 tcl proc.这个 proc 又调用了 10 个以上的 proc.

In my main tcl script, I am calling a tcl proc wrapped in a catch command. This proc in-turn calls 10 more procs.

当这 10 个 proc 中的任何一个执行错误时，TCL 仍会按预期继续执行我的主脚本，我只能查看我捕获的错误消息.此错误消息可能/可能不具有决定性，足以确定 10 个 proc 中的哪一个在执行期间出错.

When there is an error in execution in any of those 10 procs, TCL still continues execution of my main script as expected and I am just able to view the error message which I captured. This error message may/may-not be conclusive enough to determine which of the 10 procs errored out during execution.

有没有办法继续捕获所有标准输出直到出现错误?我知道这可以通过将这 10 个过程中的所有消息(puts 语句)写入另一个日志文件来完成.但我很想知道是否还有其他方法.

Is there a way to still keep capturing all the stdout until the point of error? I know it can be done by writing all messages (puts statements) in those 10 procs to another log file. But I'm interested in knowing if there is any other way.

推荐答案

catch 命令根本不拦截 I/O.拦截输出，最简单也是最多的方法就是放一个channel使用 chan push 在该频道上转换.

The catch command doesn't intercept I/O at all. To intercept output, the simplest and most method is to put a channel transform on that channel with chan push.

oo::class create Capture {
    variable contents encoding
    # Implement the channel interception protocol
    method initialize {handle mode} {
        set contents {}
        return {initialize finalize write}
    }   
    method finalize handle {
        # We do nothing here
    }
    method write {handle buffer} {
        append contents $buffer
        return $buffer
    }

    # Methods for ordinary people!
    method capture {channel body} {
        set encoding [chan configure $channel -encoding]
        chan push $channel [self]
        try {
            uplevel 1 $body
        } finally {
            chan pop $channel
        }
    }
    method contents {} {
        # Careful; need the encoding as channels work with binary data
        return [encoding convertfrom $encoding $contents]
    }
}

如何使用这个类:

set capt [Capture new]
$capt capture stdout {
    puts "Hello world!"
}
puts "Captured [string length [$capt contents]] characters"
puts [lmap c [split [$capt contents] ""] {scan $c "%c"}]

输出(我假设你能识别 ASCII 码；最后的 13 10 是一个回车/换行序列):

Output (I assume you recognise ASCII codes; the 13 10 at the end is a carriage-return/new-line sequence):

Hello world!
Captured 14 characters
72 101 108 108 111 32 119 111 114 108 100 33 13 10

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