Tcl/C ffi -- example illustrating how simple one can create C-binding within tcl using ffidl

uuid-ffidl.tcl

## -------------------------------------------------------------------------------
## ::uuid -- Generate UUID
##
## Example illustrating how simple one can create C-binding within tcl using ffidl
## -------------------------------------------------------------------------------

# ::uuid creator (with on demand binding):
proc ::uuid {args} {
  # create _fdl_uuid binding to UuidCreate :
  ffidl::callout ::_fdl_uuid {pointer-var} int [ffidl::symbol rpcrt4.dll UuidCreate] stdcall
  # create wrapper (uuid as hex) :
  proc ::uuid {args} {
    set b [::binary format x16]
    # check returns RPC_S_OK(0) or RPC_S_UUID_LOCAL_ONLY(1824):
    if {[set ret [::_fdl_uuid b]] ni {0 1824}} {
      return -code error "generate UUID failed with code $ret"
    }
    if {![llength $args]} {
      binary encode hex $b
    } else {
      binary encode {*}$args $b
    }
  }
  ::uuid {*}$args
}

## ----------------------------------------------------
## Usage examples:
## ----------------------------------------------------

% uuid;     # default hex
db5c2944f9be3c4ba2956751515d706e

% uuid hex; # as hex
8f4d437a541d814484a6e023e4963ad6

% uuid uuencode
0%9!=W1FH;4^22VP>QP07RP

% uuid base64
Jz9L4ibAa0WKoRTBu41YfQ==

## More examples (works only with extended [binary encode]):

% uuid 0;  # as binary (base 0)
°ÔH¨>6‚M‰Þ^Þk§gm

% uuid basex 62; # base(x) 62
Eefwuky3GtfvPnupfi0yl2

% uuid basex 93; # base(x) 93
@Z|B.RF];@BGE$&8Rh:1

## ----------------------------------------------------
## (Last but not least) the performance:
## ----------------------------------------------------

% timerate {uuid 0}
0.973097 µs/# 983435 # 1027646 #/sec 956.978 net-ms

% timerate {uuid}
1.197945 µs/# 805353 # 834762 #/sec 964.769 net-ms