"what is the workflow you follow to design the software you're about to write? [closed]" Code Answer

when working on personal, middle-sized projects, what do you specify before starting to code?

i specify the functional specification:

• i feared that it might be too easy, if i just started coding (which is the "how"), to forget "why" and "what" i wanted to code (for "fairly complicated" software, over the months or years that it might take to develop).
• i also wanted to understand, more or less, the "scope" of what i would be developing: in order to assess approximately (to an order of magnitude):
  • how big it will be
  • whether i could finish it
  • whether it was worth starting
  • what subset of it can be developed first

for the sake of risk management i'll add that some of what i wanted to develop implied using some software that i wasn't familiar with; to minimize the risk associated with that, i also did a little throw-away prototyping.

how?

i outlined a functional specification, using pen a paper. some of what i wrote was high-level (a business-level "vision" document), and some was lower-level, more like design (some of the ui details). sometimes i stopped and puzzled about how to organize it, but then went on, reasoning that each page is more-or-less cohesive about each topic, and that i can puzzle later about how to organize the pages (much like your wiki, perhaps).

i both did and didn't specify the software architecture in advance:

• i start development with a basic architecture (a few small components) in mind, and then add code; and, as i add code, if any component gets too big and complicated then i subdivide it into several smaller components ... it's an evolutionary process ... as it says in systemantics, a complex system that works is invariably found to have evolved from a simple system that worked.
• i'm not documenting the architecture; or, rather, the only documentation of the architecture is the code itself: for example, the way in which source code is arranged into source directories, namespaces, and dlls.

i do have a theoretical justification for the architecture as it is now, but i haven't documented these reasons:

• i'm the sole developer
• the actual architecture is documented by the code
• the reasons for the architecture are in my head, and are [re]discoverable by things like the naming conventions in the source code, and the various components' dependencies

if (only if) i weren't the sole developer, then i might think it worth documenting the architecture and its rationale.

what i said above about the architecture of the software is also true of the data which the software processes.

as for testing, i code a bit and then test it; or write a test and then code the functionality which will pass that test. i'm not doing "big bang integration", i.e. months of writing without any testing.

one of the biggest weaknesses in (or thing missing from) my process is estimating effort in advance, and then tracking implementation against the estimate ... this is one of the differences between this 'personal' project process versus a paid project that i'd do for someone else commercially. i doubt whether this is good though: if estimation is a best practice commercially, then perhaps i 'should' be doing it too on a personal project.