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Dec 01 2011

Case-sensitive

As a long time programmer there is a little thing I’d like to rant about: case-sensitivity.

For the uninitiated this is the thing that makes your program think that the variable called “MyVariable” is different from the variable called “myVariable” and the variable called “Myvariable”. The problem is that some computer languages have it and some computer languages don’t.

I grew up with BASIC and later FORTRAN, case-insensitive languages which do the natural thing and assume that capitalisation does not matter. Other languages (C#, Java, C, Matlab) are not so forgiving and insist that “a” and “A” refer to two completely different things. In real life this feels like a wilful act of obstinacy, the worst excesses of teenage pedantry, it is a user experience fail.

The origins of case-sensitivity lie in the origins of the language C in the early 1970s,  FORTRAN doesn’t have it because when it was invented, in the dawn of computing, teletype printers did not support lowercase – there was no space on the print head.  I still think of FORTRAN as a language written in ALL CAPS and so rather IMPERATIVE.

There is an argument for case-sensitivity from the point of view of compactness; mathematicians, even of my relatively lowly level will name their variables in equations with letters from the Roman and Greek alphabets, subscripts and superscripts. My father, an undergraduate mathematician, even went as far as Cyrillic alphabet. Sadly the print media, even New Scientist, do not support such typographically extravagance.

It’s even worse when your language is dynamically-typed, that’s to say it allows you to create variables willy-nilly as you write your program rather than statically-typed languages which demand you tell them explicitly of the introduction of new variables. In a statically typed language if you start with a variable called “MyVariable” and later introduce “Myvariable”, by a slip of the key, then the compiler will kick-off: complaining it has no knowledge of this interloper. A dynamically-typed language will accept this new introduction silently, giving it a default value and causing untold damage in subsequent calculations.

It’s not like case-sensitivity is used in any syntactically meaningful manner: to a computer there is no practical difference between “foo” and “Foo” – the standard placeholder function name, foo” and “Foo” to the computer are simply the label you have stuck to a box containing a thing. There are some human conventions, but they are just that – and as with any convention they are honoured as much in the breech as the observance. The compiler doesn’t care.

I must admit to a fondness of CamelCase: capitalising the initial letters of each word in a long variable name, I do it in my hashtags on twitter. In the old days of FORTRAN no such fripperies existed, not only were your variable names limited in case but also in length: you had 6 characters to work your magic.

This is to ignore the many and varied uses different uses that computer languages find for brackets: {}, (), [] and even <>.

3 comments

  1. Phil Ruse

    Ah yes, the fun I’ve had tracking down strange JavaScript behaviour only to find it was because I declared the variable in a different case to how I used it – hence, camelCase here too – when I remember!

  2. Clare D

    Ah, takes me back. My one foray into FORTRAN was such a disaster… Hours of work punching cards, leaving them some place for the machine to eat them, then coming back to find I’d left a semi-colon off and so it had ignored the whole thing. I realised right away that this relationship would lead nowhere.

  3. Ian

    @Phil Ruse – I normally work in Matlab which allows you to accidentally introduce new variables as you go. Can’t think why anyone believes case-sensitivity is a good idea!

    @Clare D – I think I’m the first post-punchcard generation. We did have a teletype at home for a bit (AEA surplus) with a paper tape reader but we never used it. Modern programming tools are fab though: Visual Studio for C# has an awful lot of auto-completion which reduces the error-rate

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