Walter:
The slides: http://www.slideshare.net/dcacm/patterns-of-human-error
Nice. Please put your PDFs everywhere but Slideshare. I'd love a simple link to
just the PDF, thank you very much (Slideshare requires Flash, JavaScript, other
things, and the flash viever doesn't allow me copypaste of URLs like that
joelonsoftware.com one or snippets that I have to copy manually here).
-
- 9V battery: it has keyd connectors *and* inverting its polarity often doesn't
lead to large damages (you may damage the curcuit in some cases). This means
that a car batter has to be designed *safer* than a 9V battery because an error
often causes more damages than in 9V batteries.
-
Simple fix: make l suffix illegal. No more possibility of this error. End of
story.
This is exactly the solution used by JSF-AV. They use a pre-compiler that
generates a compile error if you use l as suffix (and maybe even if you use
it as variable name). So they aren't using normal C++.
-
int i = 1_000_000;
A downside of the current implementation is visible here:
long i = 1_000_000_00_000L;
The underscores are not enforced every 3 (or 4 on hex/binary literals) digits.
But in practice this has not caused me troubles, so far.
-
Error Patterns Eliminated [Slide 32]
It's a very nice slide :-)
-
i should be size_t [Slide 31]
Something related to this has caused me a not immediately visible bug in D,
this is the original correct function:
double[][] matgen(int n) {
double[][] a;
double tmp = 1.0 / n / n;
a.length = n;
for (int i = 0; i n; ++i) a[i].length = n;
for (int i = 0; i n; ++i)
for (int j = 0; j n; ++j)
a[i][j] = tmp * (i - j) * (i + j);
return a;
}
Second improved version:
double[][] matgen(int n) {
double tmp = 1.0 / n / n;
auto a = new double[][](n, n);
foreach (i, row; a)
foreach (j, ref x; row)
x = tmp * (i - j) * (i + j);
return a;
}
Problem: (i - j) gives a wrong result because i and j are now unsigned.
See some of the discussion:
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D.learnarticle_id=26563
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D.learnarticle_id=26587
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D.learnarticle_id=26629
-
Uninitialized memory [Slide 41]
This compiles with no errors, but maybe you meant heap memory:
@safe void main() { int x = void; }
-
Validated data: validated!(T) [Slide 46]
I don't remember/know what this is.
Thank you for all this stuff you give us for free, people used to pay for such
texts.
-
http://www.joelonsoftware.com/articles/wrong.html
From the blog post:
All strings that come from the user must be stored in variables (or database
columns) with a name starting with the prefix us (for Unsafe String). All
strings that have been HTML encoded or which came from a known-safe location
must be stored in variables with a name starting with the prefix s (for Safe
string).
A better solution:
http://blog.moertel.com/articles/2006/10/18/a-type-based-solution-to-the-strings-problem
Bye,
bearophile
