cmStringLength.py

import lx
import lxu.meta

class StringLength(lxu.meta.ChannelModifier):
    def init_chan(self, desc):
        desc.add ("input", lx.symbol.sTYPE_STRING)
        desc.chmod_value (lx.symbol.fCHMOD_INPUT)

        desc.add ("length", lx.symbol.sTYPE_INTEGER)
        desc.chmod_value (lx.symbol.fCHMOD_OUTPUT)

    def eval(self, chans):
        string = chans.input.GetString()
        
        if isinstance(string, str):
            chans.length.SetInt(len(string))
        else:
            chans.length.SetInt(0)

chmod_meta = lxu.meta.Meta_ChannelModifier("cmStringLength", StringLength)
lxu.meta.MetaRoot(chmod_meta)