ModuleCount Metrics
The ModuleCount metrics classify the modules (a generic name for
anything that might be considered a separate entity) used in the
system. A module is "used" whenever it is
mentioned in the system code. The classification distinguishes modules that
are in the standard library ("SL"), modules in the system ("UD" - user
defined), and any remaining modules ("TP" - third party). Modules are also
classified according to what "kind" they are, namely: primitives ("P"),
classes ("C"), interfaces ("I"), enums ("E"), annotations ("A"), and
exceptions ("Ex"). An early go at the rationale for why these metrics might
be useful can be found in
an essay I
wrote.
There are a number of combinations possible, namely:
- P is the number of primitive types used in the system.
- SLC is a zero-indexed vector representing classes from the JDK
("Standard Library"), where SLC[i] is the number of i-nested classes. SLE,
SLI, SLA, SLEx, SLUnk are vectors similarly representing Enums, Interfaces,
Annotations, Exceptions, and Unknown from the JDK respectively.
- TPC is a zero-indexed vector representing third-party classes,
where where TPC[i] is the number of i-nested classes. TPE, TPI, TPA, TPEx,
TPUnk
are vectors similarly representing third-party Enums, Interfaces,
Annotations, Exceptions, and Unknown respectively.
- UDC is a zero-indexed vector representing User Defined classes,
where where UDC[i] is the number of i-nested classes. UDE, UDI, UDA, UDEx, UDUnk
are vectors similarly representing user defined Enums, Interfaces,
Annotations, Exceptions and Unknown respectively.
The need for "unknown" is because it is often the case that a module
A refers to module B, but the definition of module B is not provided
(even for user defined modules). Often the kind of module it is can
be determined by context, but sometimes they can't — hence the
need for "unknown".
Example
Below are the measurements for jgraph
version 5.7.4.3.
| SLP |
SLC |
SLI |
SLE |
SLA |
SLEx |
SLUnk |
TPC |
TPI |
TPE |
TPA |
TPEx |
TPUnk |
UDC |
UDI |
UDE |
UDA |
UDEx |
UDUkn |
| 9 |
96,7 |
32,1 |
0 |
0 |
13 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
36,37 |
14,3 |
0 |
0 |
0 |
0 |
This indicates that all 9 primitive types were used, reference was
made to 96 top-level JRE classes and 7 level-1 nested JRE classes.
Also from the JRE are 32 top-level and 1 level-1 nested interfaces,
and 13 top-level exceptions. There are no third party modules used
at all. Of the modules identified as being in jgraph,
36 are top-level classes, 37 are level-1 nested classes, 14 are
top-level interfaces, and 3 are level-1 nested interfaces.
Further Information
- Essay
on measuring the size of system (gives more measurements).
-
The Summary Inheritance metrics are
proportions. The denominators are determined using the
Module Count metrics.