8.5 Control Structures – catch

[90] catch … ?optdictvar?, extended return

Features needed to make control commands implemented in Tcl indistinguishable from control commands in C.

Access to previously inaccessible information like -errorline. General return option retrieval and signaling → Hide internals completely

More control over where return codes apply

return -code break -level 0 ↔ break

return -code break -level 1 ↔ Proc calling this acts as break.