I've been developing software for quite a few years. One of the issues that seems to come up again and again in my work is this concept of design and implementation. I recall it being a significant part of my education at the University of Waterloo's Computer Engineering program as well. The message was always the same. Never write code first. First you must design software by writing a design document, flow charts, pseudo-code, timing charts... then it's merely a trivial matter of implementing it. Make note of the attitude here given towards implementing. The real work is in the design, and it's just a trivial matter of implementing it. It sounds so simple doesn't it? Now, how often does this work out in real life?
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Member since:2006-01-10
"Similarly, source code is merely an expression of design.
And that, my friend, is as you so eloquently described without realizing it why source code is implementation.
"
Ummm... unless you plan to have some abstract notion of design that is not expressed... I don't know what you're implying here.
Source code is an expression of a design.
An English document can be an expression of design.
A drawing can be an expression of design.
Mathematical notation can be an expression of design.
Flow-charts are an expression of design.
GUI designers are an expression of design. (we do have 'compilers' for them, so you don't have to write the source code to draw the GUI often times)
For this domain (algorithms...) source code is a very good language for design. You would spend more time and introduce vagueness writing it in English than you would specifying it in source.
This is not to say that other levels of design (high-level, architecture, timing diagrams...) are not needed. They are, but they only aid you in designing the source code that you finally give to the implementer, which produces the final result.
Member since:
2007-08-22
And that, my friend, is as you so eloquently described without realizing it why source code is implementation.
The problem with source code is that it only states what actually happens, it does not carry intent. And that is the difference between design and implementation.
Design carries the intent of what is desired; implementation makes that intent a reality by trying to match what is desired as closely as possible.
Different programming languages have different sets of limitations - for instance, C vs. Java vs. Assembly vs. HTML. Some of those languages would be utterly prohibitive for many programs (e.g. HTML). Likewise, implementations can be tweaked to provide certain characteristics that designs cannot - e.g. having a mixed language program, calling out to assembly from C, C++, etc.
By contrast, English vs. Greek vs. Chinese have no limitations in themselves other than what culture puts behind it. What can be said in English can be nearly as expressly said in Greek or Chinese if one is fluent in the others, but not so by someone who is not perfectly fluent in both the original and translated versions.
But again, I'll appeal to the post of which I am replying for an excellent view of why source code IS implementation and NOT completely design.