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§18.35. Printing a parser error

1. When it happens. The parser is the part of the run-time software, included in all works produced by Inform, which tries to match the player's command against the grammar provided by the work. When it is unable to make a valid match, the parser prints an error to the player: for instance,

That's not a verb I recognise.

There are more than twenty possible messages. The one which the parser wants to say is stored in the variable "latest parser error", which has the convenient kind "command parser error". This has the following possible values:

didn't understand error
only understood as far as error
didn't understand that number error
can't see any such thing error
said too little error
aren't holding that error
can't use multiple objects error
can only use multiple objects error
not sure what it refers to error
excepted something not included error
can only do that to something animate error
not a verb I recognise error
not something you need to refer to error
can't see it at the moment error
didn't understand the way that finished error
not enough of those available error
nothing to do error
referred to a determination of scope error
I beg your pardon error
noun did not make sense in that context error
can't again the addressee error
comma can't begin error
can't see whom to talk to error
can't talk to inanimate things error
didn't understand addressee's last name error

2. The default behaviour. Prints the message in question.

3. Examples. (a) Perhaps for newcomers:

paste.png After printing a parser error:
    say "If you are new to interactive fiction, you may like to try typing HELP."

(b) Or to give the parser a certain amount of character:

paste.png Rule for printing a parser error when the latest parser error is the I beg your pardon error:
    say "What's that? Speak up, speak up." instead.

paste.png Rule for printing a parser error:
    say "That's a rum thing to say, and no mistake." instead.

(c) This can be helpful for seeing what's going on:

paste.png Rule for printing a parser error:
    say "The [latest parser error] happened.";
    continue the activity.

arrow-up.png Start of Chapter 18: Activities
arrow-left.png Back to §18.34. Implicitly taking something
arrow-right.png Onward to §18.36. Deciding whether all includes

Creating a more sensible parser error than "that noun did not make sense in this context".

Storing an invalid command to be repeated as text later in the game.