[Rd] unlockEnvironment()?

[William Dunlap]

R lets one lock an environment with both an R function,
base::lockEnvironment, and a C function, R_LockEnvironment, but, as far as
I can tell, no corresponding function to unlock an environment.  Is this
omission on principle or just something that has not been done yet?

I ask because several packages, including the well-used R6 and rlang
packages, fiddle with some bits in with SET_ENVFLAGS and ENVFLAGS to unlock
an environment.  (See grep output below.)

About 5000 (1/3 of CRAN) packages depend on R6 or rlang.  Should R supply a
more disciplined way of unlocking an environment?

Bill Dunlap
TIBCO Software
wdunlap tibco.com

$ { find . -type f -print0 | xargs -0 grep -n -C 2 ENVFLAGS ; } 2>/dev/null
./R6/tests/manual/encapsulation.R-5-unlockEnvironment <-
cfunction(signature(env = "environment"), body = '
./R6/tests/manual/encapsulation.R-6-  #define FRAME_LOCK_MASK (1<<14)
./R6/tests/manual/encapsulation.R:7:  #define FRAME_IS_LOCKED(e)
(ENVFLAGS(e) & FRAME_LOCK_MASK)
./R6/tests/manual/encapsulation.R:8:  #define UNLOCK_FRAME(e)
SET_ENVFLAGS(e, ENVFLAGS(e) & (~ FRAME_LOCK_MASK))
./R6/tests/manual/encapsulation.R-9-
./R6/tests/manual/encapsulation.R-10-  if (TYPEOF(env) == NILSXP)
./BMA/R/iBMA.glm.R-21-*/
./BMA/R/iBMA.glm.R-22-#define FRAME_LOCK_MASK (1<<14)
./BMA/R/iBMA.glm.R:23:#define FRAME_IS_LOCKED(e) (ENVFLAGS(e) &
FRAME_LOCK_MASK)
./BMA/R/iBMA.glm.R:24:#define UNLOCK_FRAME(e) SET_ENVFLAGS(e, ENVFLAGS(e) &
(~ FRAME_LOCK_MASK))
./BMA/R/iBMA.glm.R-25-'
./BMA/R/iBMA.glm.R-26-
--
./BMA/R/iBMA.surv.R-22-*/
./BMA/R/iBMA.surv.R-23-#define FRAME_LOCK_MASK (1<<14)
./BMA/R/iBMA.surv.R:24:#define FRAME_IS_LOCKED(e) (ENVFLAGS(e) &
FRAME_LOCK_MASK)
./BMA/R/iBMA.surv.R:25:#define UNLOCK_FRAME(e) SET_ENVFLAGS(e, ENVFLAGS(e)
& (~ FRAME_LOCK_MASK))
./BMA/R/iBMA.surv.R-26-'
./BMA/R/iBMA.surv.R-27-
./pkgload/src/unlock.c-20-*/
./pkgload/src/unlock.c-21-#define FRAME_LOCK_MASK (1 << 14)
./pkgload/src/unlock.c:22:#define FRAME_IS_LOCKED(e) (ENVFLAGS(e) &
FRAME_LOCK_MASK)
./pkgload/src/unlock.c:23:#define UNLOCK_FRAME(e) SET_ENVFLAGS(e,
ENVFLAGS(e) & (~FRAME_LOCK_MASK))
./pkgload/src/unlock.c-24-
./pkgload/src/unlock.c-25-extern SEXP R_TrueValue;
./SOD/src/tmp.cpp-11394-SEXP (ENCLOS)(SEXP x);
./SOD/src/tmp.cpp-11395-SEXP (HASHTAB)(SEXP x);
./SOD/src/tmp.cpp:11396:int (ENVFLAGS)(SEXP x);
./SOD/src/tmp.cpp:11397:void (SET_ENVFLAGS)(SEXP x, int v);
./SOD/src/tmp.cpp-11398-void SET_FRAME(SEXP x, SEXP v);
./SOD/src/tmp.cpp-11399-void SET_ENCLOS(SEXP x, SEXP v);
--
./SOD/src/tmp.h-11393-SEXP (ENCLOS)(SEXP x);
./SOD/src/tmp.h-11394-SEXP (HASHTAB)(SEXP x);
./SOD/src/tmp.h:11395:int (ENVFLAGS)(SEXP x);
./SOD/src/tmp.h:11396:void (SET_ENVFLAGS)(SEXP x, int v);
./SOD/src/tmp.h-11397-void SET_FRAME(SEXP x, SEXP v);
./SOD/src/tmp.h-11398-void SET_ENCLOS(SEXP x, SEXP v);

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