intfiction.org

I have a use for the Metric Units extension, but I am not really all that conversant in metric units and I don't care too much about rounding errors, so I'd like to be able to say things in the source like "the height of a person is usually about 5 foot 6" and have Inform convert this into 167.64 centimeters (give or take) for me, but I can't seem to figure out how to make this happen. I tried:



But Inform says:


What is the magic syntax that makes this work?

ETA: After experimenting, it seems that to really get the calculations right, the functions have to be like this:

It will let me assign the result using "let" and can print them out using "say", but I can't use it as a default value or in any phrase using "is". This is very tiresome.

How do you use the units in the game? If you're not using metric units it seems to me you should just use imperial units as the basis instead of trying to convert them under the hood to metric. I'm not very familiar with the Metric Units extension but I have the impression that it just defines the units, but doesn't offer any additional features you couldn't do without it.

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Vorple UI library — Beta testing site — Blog

Fortunately, I7 makes provision for expressing the same kov using what it calls "equivalent notations" (see ch 14.5, very bottom of page). Unfortunately, it doesn't seem to support multi-part notations for these equivalents, so "6 ft 5" is out. (This looks like a bug -- I'm going to mess around with it some more and start another thread to see if anyone has any insights before reporting it.) Note that you can use both feet and inches as equivalents for already declared metric units, just not together:

HTH,

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Skinny Mike

To get rid of the rounding error, you could first define a new metric unit that's 0.1mm, and base the imperial units off that. This will reduce the upper end of the range for metric units (from about 2100km to about 210km), so it depends on what sort of thing you want to measure.

Ahh, thanks, I might try that.

Looking back at it (and being slightly less irked by it now), I note that I can use the "about X foot Y" notation in the other decides (I must have forgotten the "about" one of the times I rewrote it, like I did in the original code, but I7 error messages are not real helpful for figuring out syntax errors), and it can also be used with "now". If you try to use a variable with an initialization or a default value, you get a message about how it's not good to start things off with a variable value that can change, and if you try to initialize one variable to another, you get "At the start of play, variable values have to be set equal to definite constants, so this is not allowed."

Maybe it treats the results of functions as variables, even if they use constant arguments, because they could, in theory, try to access or modify global state variables that might not have been initialized yet? I guess there isn't any kind of way to declare a const function which explicitly doesn't modify anything?

That's right. I7 doesn't have a notion of functions that are stateless or safe at compile time.