Prototype of Nix integration and solc picking

libexec/dapp/dapp

@@ -4,6 +4,28 @@ export DAPP_SRC=${DAPP_SRC-src}
 export DAPP_LIB=${DAPP_LIB-lib}
 export DAPP_OUT=${DAPP_OUT-out}
 
+function have() { command -v "$1" >/dev/null 2>&1 ; }
+
+for dep in bc curl git node solc ethabi ethrun seth jshon; do
+  if ! have $dep; then missing+=($dep); fi
+done
+
+if [ ${#missing[@]} -gt 0 ]; then
+  echo >&2 "${0##*/}: missing dependencies"
+  echo >&2
+  cat <<-EOF
+If you want to install missing dependencies by hand,
+then answer no to the following and install the following:
+
+    ${missing[@]}
+
+But we recommend that you let Dapp manage its own tools,
+and answer yes to the following.
+EOF
+
+  exec "${0##*/}-nix-setup"
+fi
+
 version=$(solc --version)
 if grep -q 0.4.9 <<<"$version"; then
   echo >&2 "${0##*/}: error: solc 0.4.9 not supported"

libexec/dapp/dapp---use

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+set -e
+
+function usage() {
+  echo >&2 "Usage: dapp --use <spec> <subcommand>..."
+  echo >&2 "Example:"
+  echo >&2
+  echo >&2 "  $ dapp --use solc:0.4.11 test"
+  echo >&2
+  exit 1
+}
+
+[[ "$#" > 0 ]] || usage
+
+function have() { command -v "$1" >/dev/null 2>&1 ; }
+if ! have nix-shell; then exec dapp nix-setup; fi
+
+export NIX_PATH=dapphub=$HOME/.nix-defexpr/channels/dapphub:$NIX_PATH
+BINARY_CACHE=$(cat ~/.nix-defexpr/channels/binary-caches/dapphub)
+
+shopt -s extglob
+case $1 in
+  solc:[0-9].+([0-9.]))
+    version=${1#solc:}
+    version=${version//./_}
+    override+=" solc = solc-versions.solc_$version;"
+    ;;
+  *)
+    echo >&2 "${0##*/}: unrecognized package spec: $1"
+    exit 1
+esac
+shift
+
+[[ "$#" > 0 ]] || usage
+
+nix-shell \
+ --option binary-caches "$BINARY_CACHE" \
+  -p "with import <dapphub> {}; dapp.override {$override }" \
+  --run "dapp $*"

libexec/dapp/dapp-nix-setup

@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+set -e
+
+function verify() {
+  read -e -p "$1 [y/n] " answer
+  [[ $answer == y ]] || [[ $answer == yes ]]
+}
+
+if ! command -v nix-env >/dev/null 2>&1; then
+  echo >&2 
+ cat >&2 <<"EOF"
+Dapp uses the Nix package manager to manage external tools.
+
+Nix is a very useful meta-tool.  All of its tools will be
+self-contained in the /nix directory in a robust way.
+
+We can launch the automatic Nix installer that works on both Linux and
+OS X.
+
+If you want to educate yourself first, please visit the Nix website
+and become convinced of its wholesome and beneficial nature.
+
+                   https://nixos.org/nix
+
+EOF
+  if verify "Install Nix?"; then
+    if ! command -v curl >/dev/null 2>&1; then
+      echo >&2
+      echo >&2 "Error: please first install curl."
+      exit 1
+    fi
+    if ! command -v bzcat >/dev/null 2>&1; then
+      echo >&2
+      echo >&2 "Error: please first install bzip2."
+      exit 1
+    fi
+
+    echo >&2
+    curl https://nixos.org/nix/install | bash
+
+    echo >&2 "${0##*/}: Congratulations -- Nix is installed."
+    if verify "Setup shell profile?"; then
+      ( set +x
+        echo ". ~/.nix-profile/etc/profile.d/nix.sh" >> ~/.profile
+      )
+    fi
+
+    . ~/.nix-profile/etc/profile.d/nix.sh
+
+    echo >&2 "${0##*/}: Configuring the DappHub channel..."
+    nix-channel --add https://nix.dapphub.com/pkgs/dapphub
+    nix-channel --update
+
+    echo >&2 "${0##*/}: Installing dapp via Nix..."
+    nix-env -iA dapphub.dapp
+
+    echo >&2 "${0##*/}: Excellent!  Log out or run the following:"
+    echo >&2
+    echo >&2 "    source ~/.nix-profile/etc/profile.d/nix.sh"
+    echo >&2
+    echo >&2 "and you will be fully set up to develop dapps."
+  fi
+fi