Can't find a 'length' data name in a datamap

Question

I'm going to say this upfront; the coding throwing this error probably shouldn't be throwing the aforementioned error, and it's concerning me that it is.

Here is the coding I use for my load game:

{(link-reveal: "Load a Saved Crawl")[
	(set: _saves to (saved-games:))
	(if: _saves's length < 1)[
		You don't have any saved games.]\
	(if: _saves's length > 0)[
		(for: each _name, ...(datanames: _saves))[
		<br>
			(print: 
				"(link: 'Load Crawl: " + (_saves's (_name)) + "')[" +
					"(load-game: '" + _name + "')" +		
				"]"
			)
		]
	]
]}

For some reason, my attempts at checking for the _save's length (to make sure that there is a save file to be accessed) always throws this error: 

I can't find a 'length' data name in a datamap►I tried to access a value in a string/array/datamap, but I couldn't find it.

 

This is highly frustrating, because it results in both the "You don't have any saved games." error message and my saved game for 'Goethi', my test character.

Answer 1

The String and Array data types have both have a length property because they both contain a sequence of values, in the case of a String those values are Characters, and the length peoperty is used to determine how long that sequence is.

The Datamap data type is a collection of name & value pairs. To determine how many pairs are in the collection you would generally count the names, and the simplest way to do that is to first use the (datanames:) to obtain an Array of names which you can then get the length of.

(set: _saves to (saved-games:))
(set: _names to (datanames: _saves))
count: (print: _names's length)

So knowing the above information your example would look more like.

{(link-reveal: "Load a Saved Crawl")[
	(set: _saves to (datanames: (saved-games:)))
	(if: _saves's length is 0)[
		You don't have any saved games.]\
	(else:)[
		(for: each _name, ..._saves)[
			<br>
			(print: 
				"(link: 'Load Crawl: " + _name + "')[" +
					"(load-game: '" + _name + "')" +		
				"]"
			)
		]
	]
]}