Python3.5 compat (#794)

Summary:
See #467. Ping myleott to review.

This is a work-related contribution. Ping lark to review.
Pull Request resolved: https://github.com/pytorch/fairseq/pull/794

Differential Revision: D15756816

Pulled By: myleott

fbshipit-source-id: 6dce3ff3a713bf5f60e5782bc260b2ca9d2c0a9b

README.md

@@ -39,7 +39,7 @@ translation and language modeling datasets.
 # Requirements and Installation
 
 * [PyTorch](http://pytorch.org/) version >= 1.0.0
-* Python version >= 3.6
+* Python version >= 3.5
 * For training new models, you'll also need an NVIDIA GPU and [NCCL](https://github.com/NVIDIA/nccl)
 
 Please follow the instructions here to install PyTorch: https://github.com/pytorch/pytorch#installation.

fairseq/data/data_utils.py

@@ -166,8 +166,8 @@ def batch_by_size(
         sample_lens.append(num_tokens_fn(idx))
         sample_len = max(sample_len, sample_lens[-1])
         assert sample_len <= max_tokens, (
-            f"sentence at index {idx} of size {sample_len} exceeds max_tokens "
-            f"limit of {max_tokens}!"
+            "sentence at index {} of size {} exceeds max_tokens "
+            "limit of {}!".format(idx, sample_len, max_tokens)
         )
         num_tokens = (len(batch) + 1) * sample_len
         if is_batch_full(num_tokens):

fairseq/models/transformer.py

@@ -280,7 +280,7 @@ class TransformerEncoder(FairseqEncoder):
             state_dict['{}.embed_positions._float_tensor'.format(name)] = torch.FloatTensor(1)
         for i in range(len(self.layers)):
             # update layer norms
-            self.layers[i].upgrade_state_dict_named(state_dict, f"{name}.layers.{i}")
+            self.layers[i].upgrade_state_dict_named(state_dict, "{}.layers.{}".format(name, i))
 
         version_key = '{}.version'.format(name)
         if utils.item(state_dict.get(version_key, torch.Tensor([1]))[0]) < 2:
@@ -540,10 +540,10 @@ class TransformerEncoderLayer(nn.Module):
         }
         for old, new in layer_norm_map.items():
             for m in ('weight', 'bias'):
-                k = f'{name}.layer_norms.{old}.{m}'
+                k = '{}.layer_norms.{}.{}'.format(name, old, m)
                 if k in state_dict:
                     state_dict[
-                        f'{name}.{new}.{m}'
+                        '{}.{}.{}'.format(name, new, m)
                     ] = state_dict[k]
                     del state_dict[k]
 

fairseq/models/transformer_from_pretrained_xlm.py

@@ -90,7 +90,7 @@ def upgrade_state_dict_with_xlm_weights(
             decoder and the pretrained_xlm_checkpoint
     """
     if not os.path.exists(pretrained_xlm_checkpoint):
-        raise IOError(f"Model file not found: {pretrained_xlm_checkpoint}")
+        raise IOError("Model file not found: {}".format(pretrained_xlm_checkpoint))
 
     state = checkpoint_utils.load_checkpoint_to_cpu(pretrained_xlm_checkpoint)
     xlm_state_dict = state["model"]
@@ -100,10 +100,12 @@ def upgrade_state_dict_with_xlm_weights(
             if search_key in key:
                 subkey = key[key.find(search_key):]
                 assert subkey in state_dict, (
-                    f"{str(state_dict.keys())} Transformer encoder / decoder "
-                    f"state_dict does not contain {subkey}. Cannot "
-                    f"load {key} from pretrained XLM checkpoint "
-                    f"{pretrained_xlm_checkpoint} into Transformer."
+                    "{} Transformer encoder / decoder "
+                    "state_dict does not contain {}. Cannot "
+                    "load {} from pretrained XLM checkpoint "
+                    "{} into Transformer.".format(
+                        str(state_dict.keys()),
+                        subkey, key, pretrained_xlm_checkpoint)
                     )
 
                 state_dict[subkey] = xlm_state_dict[key]

fairseq/tasks/multilingual_translation.py

@@ -27,14 +27,14 @@ from . import FairseqTask, register_task
 
 
 def _lang_token(lang: str):
-    return f'__{lang}__'
+    return '__{}__'.format(lang)
 
 
 def _lang_token_index(dic: Dictionary, lang: str):
     """Return language token index."""
     idx = dic.index(_lang_token(lang))
     assert idx != dic.unk_index, \
-        f'cannot find language token for lang {lang}'
+        'cannot find language token for lang {}'.format(lang)
     return idx
 
 

fairseq/tasks/semisupervised_translation.py

@@ -362,7 +362,7 @@ class SemisupervisedTranslationTask(MultilingualTranslationTask):
             for lang_pair in self.args.lang_pairs:
                 _, tgt = lang_pair.split('-')
                 sample_key = _get_denoising_dataset_key(lang_pair)
-                forward_backward(model.models[f'{tgt}-{tgt}'], sample[sample_key], sample_key, self.lambda_denoising)
+                forward_backward(model.models['{0}-{0}'.format(tgt)], sample[sample_key], sample_key, self.lambda_denoising)
 
         return agg_loss, agg_sample_size, agg_logging_output
 

fairseq/utils.py

@@ -313,7 +313,7 @@ def get_activation_fn(activation: str) -> Callable:
     elif activation == 'tanh':
         return torch.tanh
     else:
-        raise RuntimeError(f"--activation-fn {activation} not supported")
+        raise RuntimeError("--activation-fn {} not supported".format(activation))
 
 
 def get_available_activation_fns() -> List:

setup.py

@@ -35,6 +35,7 @@ setup(
     classifiers=[
         'Intended Audience :: Science/Research',
         'License :: OSI Approved :: BSD License',
+        'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Topic :: Scientific/Engineering :: Artificial Intelligence',
     ],

tests/test_binaries.py

@@ -303,7 +303,7 @@ class TestMaskedLanguageModel(unittest.TestCase):
                             "--encoder-ffn-embed-dim",
                             "32",
                             "--pretrained-xlm-checkpoint",
-                            f"{data_dir}/checkpoint_last.pt",
+                            "{}/checkpoint_last.pt".format(data_dir),
                             "--activation-fn",
                             "gelu",
                             "--max-source-positions",