brewCache.rdThese functions provide a cache system for brew templates.
brewCache(envir=NULL)
brewCacheOn()
brewCacheOff()
setBufLen(len=0)the environment to store text and R expressions for
each brewed template.
length of internal buffers for parsing the templates.
brew can cache parsed templates for potential speedup but only when brew calls are passed filenames, not connections, and when tplParser is NULL.
brew caching is implemented by storing file names, modification
times, and the associated text and R expressions in an internal
environment. Calling brewCache() with an appropriate
environment sets the internal cache. Calling without arguments
returns the internal cache. The cache is exposed this way mainly
for testing, debugging, performance improvement, etc. and this
may be off-limits in future releases.
Simple enough, brewCacheOn() turns on
caching of brew templates and is equivalent to calling
brewCache(envir=new.env(hash=TRUE,parent=globalenv())).
brewCache() without arguments returns the internal
environment. Calling brewCacheOff() turns off caching by
setting the internal environment to NULL.
One thing to note: filenames act as keys in the internal cache environment, and brew does nothing to expand them to their full paths. Thus, '/home/user/brew.html' and '~usr/brew.html' will act as separate keys, although on-disk they may actually point to the same file.
setBufLen() initializes internal parsing vectors to length len. Default is 0.
brewCache() without arguments returns the internal cache. All others invisibly return NULL.
Sweave for the original report generator.
## Turn on caching
brewCacheOn()
## Brew a template
brew(system.file("featurefull.brew",package="brew"),envir=new.env())
#> You won't see this R output, but it will run.
#> Now foo is bar and today is October 14, 2025.
#> How about generating a template from a template?
#> <%
#> foo <- 'fee fi fo fum'
#> brew <- 'haha'
#> %>
#> foo is still bar.
#> Contents of current directory:
#> [1] "brew.html" "index.html"
#>
## Get the internal cache
cache <- brewCache()
## Inspect
as.list(cache)
#> $`/tmp/RtmpzgcSH2/temp_libpath3bbc1415ec28fc/brew/featurefull.brew`
#> $`/tmp/RtmpzgcSH2/temp_libpath3bbc1415ec28fc/brew/featurefull.brew`$mtime
#> [1] "2025-10-14 14:54:50 UTC"
#>
#> $`/tmp/RtmpzgcSH2/temp_libpath3bbc1415ec28fc/brew/featurefull.brew`$env
#> <environment: 0x5569039c30b0>
#>
#>
## Inspect first file cached in list
as.list(cache)[[1]]
#> $mtime
#> [1] "2025-10-14 14:54:50 UTC"
#>
#> $env
#> <environment: 0x5569039c30b0>
#>
## Inspect environment that contains text and parsed code
as.list(as.list(cache)[[1]]$env)
#> $code
#> expression(.brew.cat(1, 1), foo <- "bar", .brew.cat(3, 4), cat(foo),
#> .brew.cat(6, 6), cat(format(Sys.time(), "%B %d, %Y")), .brew.cat(8,
#> 8), .brew.cat(13, 20), cat(foo), .brew.cat(22, 23), print(dir()),
#> .brew.cat(25, 25))
#>
#> $text
#> [1] "You won't see this R output, but it will run. "
#> [2] " foo <- 'bar' "
#> [3] "\n"
#> [4] "Now foo is "
#> [5] "foo"
#> [6] " and today is "
#> [7] "format(Sys.time(),'%B %d, %Y')"
#> [8] ".\n"
#> [9] "# Comment -- ignored -- useful in testing. \n"
#> [10] " Also notice the dash-percent-gt.\n"
#> [11] " It chops off the trailing newline. \n"
#> [12] " You can add it to any percent-gt. "
#> [13] "How about generating a template from a template?\n"
#> [14] "<%"
#> [15] " \n"
#> [16] "\tfoo <- 'fee fi fo fum' \n"
#> [17] "\tbrew <- 'haha'\n"
#> [18] "%>"
#> [19] "\n"
#> [20] "foo is still "
#> [21] "foo"
#> [22] ".\n"
#> [23] "Contents of current directory:\n"
#> [24] " print(dir()) "
#> [25] "\n"
#>
## Turn off brew caching
brewCacheOff()
rm(cache)