Entering without a noun

There are some places in my game where the player might want to say just ENTER, without a noun, because what they are entering is obvious from context and the place being entered is actually a room, not a container. I tried (for example)

Instead of entering when the location is Outside The Post Office: now the player is in The Post Office.
but the standard response is “You must supply a noun.”

and I also use the specific noun present case, which works

Instead of entering The Post Office when the location is Outside The Post Office: now the player is in The Post Office.

I suppose I could parse out the ‘enter with no noun’ case from the input line, but is there a more elegant approach?

The standard “enter” grammar is defined both with and without the noun. So you can define a “supplying a missing noun” rule to handle this case. See 18.32.

Are you not using cardinal directions in this game?

Are you only using the “enter” command when there is, in fact, only one way for the player to go from where they are?

Alternatively, you could use the “inside” and “outside” directions to link the two locations - in that case, ENTER and EXIT will automatically convert to going actions.

But sometimes that might not be worth it.

Thank you all. My inexperience is showing!

Excellent.

I’m using the cardinal directions as well, but the obviousness of Enter in one or two locations seems attractive.

I didn’t know that. Thanks.