#A better finder rename wildcards plus

The key here is that exists tests for the existence of an object in memory, basically.

If not, you’ll skip past and continue executing code. If the window object exists, you’ll fall through the branch and call doStuff. If exists (window 7 of application 'Camino') then You just know that using the command will either return you some object or result in nothing at all. You don’t really know how it works internally–it’s part of a larger library you’re using–and it doesn’t really matter. Let’s say you have an AppleScript command that returns some object. WHAT DOES THIS HAVE TO DO WITH exists? (AND OTHER COOL FACTS ABOUT GEOGRAPHY) We’re going to move away from strings for just a moment, so follow along. Because of this, we say it’s dynamically allocated. The compiler has no way to know what file the user will choose, so it can’t make the same kind of optimization–the user might pick a path whose length is 26 bytes, 67 bytes, or 900 bytes. The first version, however, requires the user to choose a file.

#A better finder rename wildcards plus

(Five characters plus one null character to mark the end of the string.) It will always be 6 bytes long when the program loads, so the compiler can gain a tiny resource gain by shoving those 6 bytes into an unchanging–static–memory location. In C, for example, “pants” is exactly 6 bytes long. (Such as an exact string typed into the source.) Compilers are smart that way–since they know how large certain data types are, they can figure out certain optimizations when given the right information. What’s the difference between dynamically and statically allocated strings? You typed the string into the source code, so the compiler knows exactly how long, in memory, the value of the variable needs to be you’ve essentially told the compiler how much data the program will need to store in memory by defining the exact string, and thus its length. IN THIS CORNER, weighing in at an UNKNOWN AMOUNT OF BYTES, is a string that is dynamically allocated during runtime: set aString to (choose file with prompt)ĪND IN THIS CORNER, weighing in at EXACTLY AS MANY BYTES AS IS NEEDED TO STORE “pants”, is a string that is statically allocated at compile time: set aString to 'pants' Strings are not an exception, and in fact they’re a really good example to get us going and lay some foundation work. I don’t think I’ve seen it discussed in detail before on the forums, but I haven’t searched for it, so I may be retreading.Įverything in programming, at some point, comes back to how memory is handled. I would like to expand on this, since newcomers typically don’t know what’s going on here. Please read hhas’s post below.Įxists is an application command. I’m leaving this post here, because it’s still somewhat informative, but its basic point about the exists command may be incorrect. It completely fooled me, because the behaviour is logical and explainable. Oops: It looks like this may actually be a bug in AppleScript, according to hhas below.