Source Code for Module topo.misc.filepath

  1  """ 
  2  Functions and classes to simplify dealing with paths. 
  3   
  4  For portable code: 
  5    - specify paths in unix (rather than Windows) style; 
  6    - use resolve_path() for paths to existing files to be read,  
  7      and normalize_path() for paths to new files to be written. 
  8   
  9  The location in which new files are created by default can be 
 10  controlled by the output_path module attribute, which applies 
 11  whenever a particular location is not specified explicitly. 
 12   
 13  $Id: filepath.py 10672 2009-10-28 01:00:50Z ceball $ 
 14  """ 
 15  __version__='$Revision: 10672 $' 
 16   
 17  import os.path 
 18  import sys 
 19   
 20  import param 
 21   
 22   
 23  # copied from scipy/weave/catalog.py (scipy svn 5552) 
 24  import socket,tempfile 
 25 -def is_writable(dir): 
 26      """Determine whether a given directory is writable in a portable manner. 
 27   
 28      :Parameters: 
 29       - dir: string 
 30         A string represeting a path to a directory on the filesystem. 
 31   
 32      :Returns: 
 33        True or False. 
 34      """ 
 35   
 36      # Do NOT use a hardcoded name here due to the danger from race conditions 
 37      # on NFS when multiple processes are accessing the same base directory in 
 38      # parallel.  We use both hostname and pocess id for the prefix in an 
 39      # attempt to ensure that there can really be no name collisions (tempfile 
 40      # appends 6 random chars to this prefix). 
 41      prefix = 'dummy_%s_%s_' % (socket.gethostname(),os.getpid()) 
 42      try: 
 43          tmp = tempfile.TemporaryFile(prefix=prefix,dir=dir) 
 44      except OSError: 
 45          return False 
 46      # The underlying file is destroyed upon closing the file object (under 
 47      # *nix, it was unlinked at creation time) 
 48      tmp.close() 
 49      return True 
 50   
 51   
 52 -class Filename(param.Parameter): 
 53      """ 
 54      Filename is a Parameter that can be set to a string specifying the 
 55      path of a file (in unix style), and returns it in the format of 
 56      the user's operating system.  Additionally, the specified path can 
 57      be absolute or relative to: 
 58       
 59      * any of the paths specified in the search_paths attribute; 
 60   
 61      * any of the paths searched by resolve_path() (see doc for that 
 62        function). 
 63      """ 
 64      __slots__ = ['search_paths']  
 65   
 66 -    def __init__(self,default=None,search_paths=[],**params): 
 67          self.search_paths = search_paths 
 68          super(Filename,self).__init__(default,**params) 
 69   
 70           
 71 -    def __set__(self,obj,val): 
 72          """ 
 73          Call Parameter's __set__, but warn if the file cannot be found. 
 74          """ 
 75          try: 
 76              resolve_path(val,self.search_paths) 
 77          except IOError, e: 
 78              param.Parameterized(name="%s.%s"%(obj.name,self._attrib_name)).warning('%s'%(e.args[0])) 
 79   
 80          super(Filename,self).__set__(obj,val) 
 81           
 82 -    def __get__(self,obj,objtype): 
 83          """ 
 84          Return an absolute, normalized path (see resolve_path). 
 85          """ 
 86          raw_path = super(Filename,self).__get__(obj,objtype) 
 87          return resolve_path(raw_path,self.search_paths) 
 88   
 89 -    def __getstate__(self): 
 90          # don't want to pickle the search_paths         
 91          state = super(Filename,self).__getstate__() 
 92          # CBALERT: uncommenting gives an error on make tests (testsnapshots.py). 
 93          # Testsnapshots.py runs fine on its own, and the snapshot-tests pass. 
 94          # Must be a test interaction? Needs investigating. 
 95          #del state['search_paths'] 
 96          return state 
 97   
 98   
 99  import topo 
100  package_path = os.path.split(topo.__file__)[0] 
101   
102  # CEBALERT: we should try to remove this as soon as possible; anything 
103  # relying on the location of the 'topographica' script should be 
104  # re-thought (removed, or changed to output_path or package_path). 
105  application_path = os.path.split(os.path.split(sys.executable)[0])[0] 
106   
107  # Location in which to create files; defaults to application_path.  If 
108  # that's not writable, uses ~/topographica (creating it if necessary). 
109  if is_writable(application_path): 
110      output_path = application_path  
111  else: 
112      home_topographica = os.path.join(os.path.expanduser("~"),'topographica') 
113      if not os.path.exists(home_topographica): 
114          os.mkdir(home_topographica) 
115      output_path = home_topographica 
116   
117   
118 -def resolve_path(path,search_paths=None): 
119      """ 
120      Find the path to an existing file, searching in the specified 
121      search paths if the filename is not absolute, and converting a 
122      UNIX-style path to the current OS's format if necessary. 
123   
124      To turn a supplied relative path into an absolute one, the path is 
125      appended to each path in (search_paths+the current working 
126      directory+the application's base path), in that order, until the 
127      file is found. 
128   
129      (Similar to Python's os.path.abspath(), except more search paths 
130      than just os.getcwd() can be used, and the file must exist.) 
131       
132      An IOError is raised if the file is not found anywhere. 
133      """ 
134      path = os.path.normpath(path) 
135   
136      if os.path.isabs(path): 
137          if os.path.isfile(path): 
138              return path 
139          else: 
140              raise IOError('File "%s" not found.'%path) 
141      else: 
142          all_search_paths = search_paths or [] + [os.getcwd()] + [output_path] + [package_path] + [application_path] 
143   
144          paths_tried = [] 
145          for prefix in all_search_paths: 
146              try_path = os.path.join(os.path.normpath(prefix),path) 
147              if os.path.isfile(try_path): return try_path 
148              paths_tried.append(try_path) 
149   
150          raise IOError('File "'+os.path.split(path)[1]+'" was not found in the following place(s): '+str(paths_tried)+'.') 
151   
152   
153 -def normalize_path(path="",prefix=None): 
154      """ 
155      Convert a UNIX-style path to the current OS's format, 
156      typically for creating a new file or directory. 
157   
158      If the path is not already absolute, it will be made 
159      absolute (using the specified prefix, which defaults 
160      to filepath.output_path) in the process. 
161   
162      (Should do the same as Python's os.path.abspath(), except 
163      using the specified prefix rather than os.getcwd().) 
164      """ 
165      if not prefix: 
166          prefix = output_path 
167           
168      if not os.path.isabs(path): 
169          path = os.path.join(os.path.normpath(prefix),path) 
170   
171      return os.path.normpath(path) 
172